WorldWideScience

Sample records for kamm impact structure

  1. Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?

    Science.gov (United States)

    Koeberl, Christian; Fredriksson, Kurt; Goetzinger, Michael; Reimold, Wolf Uwe

    1989-01-01

    Quartz pebbles from the Roter Kamm impact crater (the Namib Desert, SWA/Namibia) were examined for evidence of impact-induced hydrothermal activity, using results from microprobe analyses, neutron activation analyses, transmission IR spectroscopy, and X-ray diffractometry. It was found that the pebbles consisted of pure quartz, which contains three different types of fluid inclusions. These were identified as primary inclusions (5-10 microns) that record the formation conditions of the quartz, very small (less than 1 micron) secondary inclusions associated with the grain boundaries, and late inclusions of irregular size. It is concluded that the quartz and the primary inclusions may provide evidence for a postimpact phase of extensive hydrothermal activity, generated by the residual heat from the kinetic energy of the impact.

  2. The Karlsruhe Atmospheric Mesoscale Model KAMM; Das Karlsruher Atmosphaerische Mesoskalige Modell KAMM

    Energy Technology Data Exchange (ETDEWEB)

    Adrian, G. [Forschungszentrum Karlsruhe GmbH Umwelt und Technik (Germany). Inst. fuer Meteorologie und Klimaforschung]|[Karlsruhe Univ. (T.H.). (Germany). Inst. fuer Meteorologie und Klimaforschung

    1998-01-01

    The applications of the KAMM model range from real-time simulations over the analysis of mesoscale phenomena and the development of parametrizations to describing climatology. In the course of time, wishes emerged to change essential parts of the original model concept, calling for substantial reprogramming; so it was decided to entirely redraft the dynamic core of KAMM and to program it from the beginning including the parallelization of the code. The paper describes the basics of the new model core. (orig./KW) [Deutsch] Der Anwendungsbereich des KAMM-Modells erstreckt sich von Echtzeitsimulationen, ueber Analyse mesoskaliger Phaenomene, Entwicklung von Parametrisierungen bis hin zur beschreibenden Klimatologie. Weil im Laufe der Entstehungszeit wesentliche Aenderungswuensche des urspruenglichen Konzeptes entstanden sind, die eine Neuprogrammierung in wesentlichen Teilen erforderlich erscheinen lassen, wurde entschieden, den dynamischen Kern von KAMM voellig neu zu gestalten und bei der Programmierung eine Parallelisierung des Codes von Anfang an mit einzubeziehen. Die Grundlagen dieses neuen Modellkernes werden vorgestellt. (orig./KW)

  3. Wind Simulations for the Gulf of Suez with KAMM

    DEFF Research Database (Denmark)

    Frank, Helmut Paul

    In order to get a better overview of the spatial distribution of the wind resource in the Gulf of Suez, numerical simulations to determine the wind climate have been carried out with the Karlsruhe Atmospheric Mesoscale Model KAMM. The method and the results are described here. The simulations of ...... of the wind climate of the Gulf of Suez with KAMM capture the main features of the observed wind climate. The mean wind speed and energy flux density are somewhat underpredicted....

  4. Kamm on Inviolability and Agent-Relative Restrictions

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper

    2009-01-01

    Abstract  Agent-relative restrictions prohibit minimizing violations: that is, they require us not to minimize the total number of their violations by violating them ourselves. Frances Kamm has explained this prohibition in terms of the moral worth of persons, which, in turn, she explains in terms...

  5. The numerical wind atlas - the KAMM/WAsP method

    DEFF Research Database (Denmark)

    Frank, H.P.; Rathmann, Ole; Mortensen, Niels Gylling

    2001-01-01

    The method of combining the Karlsruhe Atmospheric Mesoscale Model, KAMM, with the Wind Atlas Analysis and Application Program, WAsP, to make local predictions of the wind resource is presented. It combines the advantages of mesoscale modeling - overviewover a big region and use of global data bases...

  6. Concrete structures under projectile impact

    CERN Document Server

    Fang, Qin

    2017-01-01

    In this book, the authors present their theoretical, experimental and numerical investigations into concrete structures subjected to projectile and aircraft impacts in recent years. Innovative approaches to analyze the rigid, mass abrasive and eroding projectile penetration and perforation are proposed. Damage and failure analyses of nuclear power plant containments impacted by large commercial aircrafts are numerically and experimentally analyzed. Ultra-high performance concrete materials and structures against the projectile impact are developed and their capacities of resisting projectile impact are evaluated. This book is written for the researchers, engineers and graduate students in the fields of protective structures and terminal ballistics.

  7. Simulating structural response to water impact

    OpenAIRE

    Campbell, James C; Vignjevic, Rade

    2012-01-01

    Structural response to water impact is important for several areas, including the aerospace and marine industries. Aircraft must be designed to cope with ditching and offshore structures are subject to extreme wave impact and green water loading. The goal is a reliable technique for predicting the structural response to extreme water loading. This is a complex problem involving the interaction of non-linear fluid behaviour (breaking waves, fluid impact) with non-linear structural behaviour (l...

  8. Impact structures in Africa: A review

    Science.gov (United States)

    Reimold, Wolf Uwe; Koeberl, Christian

    2014-05-01

    More than 50 years of space and planetary exploration and concomitant studies of terrestrial impact structures have demonstrated that impact cratering has been a fundamental process - an essential part of planetary evolution - ever since the beginning of accretion and has played a major role in planetary evolution throughout the solar system and beyond. This not only pertains to the development of the planets but to evolution of life as well. The terrestrial impact record represents only a small fraction of the bombardment history that Earth experienced throughout its evolution. While remote sensing investigations of planetary surfaces provide essential information about surface evolution and surface processes, they do not provide the information required for understanding the ultra-high strain rate, high-pressure, and high-temperature impact process. Thus, hands-on investigations of rocks from terrestrial impact craters, shock experimentation for pressure and temperature calibration of impact-related deformation of rocks and minerals, as well as parameter studies pertaining to the physics and chemistry of cratering and ejecta formation and emplacement, and laboratory studies of impact-generated lithologies are mandatory tools. These, together with numerical modeling analysis of impact physics, form the backbone of impact cratering studies. Here, we review the current status of knowledge about impact cratering - and provide a detailed account of the African impact record, which has been expanded vastly since a first overview was published in 1994. No less than 19 confirmed impact structures, and one shatter cone occurrence without related impact crater are now known from Africa. In addition, a number of impact glass, tektite and spherule layer occurrences are known. The 49 sites with proposed, but not yet confirmed, possible impact structures contain at least a considerable number of structures that, from available information, hold the promise to be able to expand

  9. The Impact of Sound Structure on Morphology

    DEFF Research Database (Denmark)

    Laaha, Sabine; Kjærbæk, Laila; Basbøll, Hans

    2011-01-01

    This study examines the impact of sound structure on children’s acquisition of noun plural morphology, focussing on stem change. For this purpose, a threelevel classification of stem change properties according to sound structure is presented, with increasing opacity of the plural stem: no change...

  10. The Impact of Sound Structure on Morphology

    DEFF Research Database (Denmark)

    Laaha, Sabine; Kjærbæk, Laila; Basbøll, Hans

    2011-01-01

    This study examines the impact of sound structure on children’s acquisition of noun plural morphology, focussing on stem change. For this purpose, a threelevel classification of stem change properties according to sound structure is presented, with increasing opacity of the plural stem: no change...

  11. Phenotypic impact of genomic structural variation

    DEFF Research Database (Denmark)

    Weischenfeldt, Joachim; Symmons, Orsolya; Spitz, François;

    2013-01-01

    Genomic structural variants have long been implicated in phenotypic diversity and human disease, but dissecting the mechanisms by which they exert their functional impact has proven elusive. Recently however, developments in high-throughput DNA sequencing and chromosomal engineering technology have...... facilitated the analysis of structural variants in human populations and model systems in unprecedented detail. In this Review, we describe how structural variants can affect molecular and cellular processes, leading to complex organismal phenotypes, including human disease. We further present advances...

  12. Structural Health Monitoring for Impact Damage in Composite Structures.

    Energy Technology Data Exchange (ETDEWEB)

    Roach, Dennis P.; Raymond Bond (Purdue); Doug Adams (Purdue)

    2014-08-01

    Composite structures are increasing in prevalence throughout the aerospace, wind, defense, and transportation industries, but the many advantages of these materials come with unique challenges, particularly in inspecting and repairing these structures. Because composites of- ten undergo sub-surface damage mechanisms which compromise the structure without a clear visual indication, inspection of these components is critical to safely deploying composite re- placements to traditionally metallic structures. Impact damage to composites presents one of the most signi fi cant challenges because the area which is vulnerable to impact damage is generally large and sometimes very dif fi cult to access. This work seeks to further evolve iden- ti fi cation technology by developing a system which can detect the impact load location and magnitude in real time, while giving an assessment of the con fi dence in that estimate. Fur- thermore, we identify ways by which impact damage could be more effectively identi fi ed by leveraging impact load identi fi cation information to better characterize damage. The impact load identi fi cation algorithm was applied to a commercial scale wind turbine blade, and results show the capability to detect impact magnitude and location using a single accelerometer, re- gardless of sensor location. A technique for better evaluating the uncertainty of the impact estimates was developed by quantifying how well the impact force estimate meets the assump- tions underlying the force estimation technique. This uncertainty quanti fi cation technique was found to reduce the 95% con fi dence interval by more than a factor of two for impact force estimates showing the least uncertainty, and widening the 95% con fi dence interval by a fac- tor of two for the most uncertain force estimates, avoiding the possibility of understating the uncertainty associated with these estimates. Linear vibration based damage detection tech- niques were investigated in the

  13. Materials and structures under shock and impact

    CERN Document Server

    Bailly, Patrice

    2013-01-01

    In risk studies, engineers often have to consider the consequences of an accident leading to a shock on a construction. This can concern the impact of a ground vehicle or aircraft, or the effects of an explosion on an industrial site.This book presents a didactic approach starting with the theoretical elements of the mechanics of materials and structures, in order to develop their applications in the cases of shocks and impacts. The latter are studied on a local scale at first. They lead to stresses and strains in the form of waves propagating through the material, this movement then extending

  14. Numerical Modeling of the Araguainha Impact Structure, Brazil

    Science.gov (United States)

    Vasconcelos, M. A. R.; Crósta, A. P.; Wünnemann, K.; Collins, G. S.; Reimold, W. U.; Köster, P.

    2016-08-01

    The Araguainha structure is the largest complex impact structure in South America. It was formed in sedimentary rocks overlaying a granitic basement.We used the iSALEcode to simulate the formation of the Araguainha impact structure.

  15. Analysis of flexible structures under lateral impact

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, D. F. [Paul C. Kizzo and Associates Inc., Seismic Structural Group, Oakland, CA 94612 (United States); Razavi, H. [AREVA Inc., Civil Seismic Group, San Jose, CA 95119 (United States)

    2012-07-01

    Three methods for analysis of flexible structures under lateral impact are presented. The first proposed method (Method A) consists of: (1) modifying an available deceleration on a rigid target with conservation principles to account for structural flexibility; and (2) transient nonlinear analysis of the structure with the corrected forcing function. The second proposed method (Method B) is similar to Method A in obtaining the forcing function but it solves the equations of motion of an idealized two-degree-of-freedom system instead of directly using conservation principles. The last method simply provides the maximum force in the structure using the conservation of energy and linear momentum. A coupled simulation is also performed in LS-DYNA and compared against the proposed methods. A case study is presented to illustrate the applicability of all three methods and the LS-DYNA simulation. (authors)

  16. Impact of silk biomaterial structure on proteolysis.

    Science.gov (United States)

    Brown, Joseph; Lu, Chia-Li; Coburn, Jeannine; Kaplan, David L

    2015-01-01

    The goal of this study was to determine the impact of silk biomaterial structure (e.g. solution, hydrogel, film) on proteolytic susceptibility. In vitro enzymatic degradation of silk fibroin hydrogels and films was studied using a variety of proteases, including proteinase K, protease XIV, α-chymotrypsin, collagenase, matrix metalloproteinase-1 (MMP-1) and MMP-2. Hydrogels were used to assess bulk degradation while films were used to assess surface degradation. Weight loss, secondary structure determined by Fourier transform infrared spectroscopy and degradation products analyzed via sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used to evaluate degradation over 5 days. Silk films were significantly degraded by proteinase K, while silk hydrogels were degraded more extensively by protease XIV and proteinase K. Collagenase preferentially degraded the β-sheet content in hydrogels while protease XIV and α-chymotrypsin degraded the amorphous structures. MMP-1 and MMP-2 degraded silk fibroin in solution, resulting in a decrease in peptide fragment sizes over time. The link between primary sequence mapping with protease susceptibility provides insight into the role of secondary structure in impacting proteolytic access by comparing solution vs. solid state proteolytic susceptibility.

  17. The Guarda structure (Portugal): Impact structure or not? Microstructural studies of Quartz, Zircon and Monazite

    NARCIS (Netherlands)

    Zalinge, M.E. van; Hamers, M.F.; Drury, M.R.

    2012-01-01

    The Guarda Structure in north-eastern Portugal has been proposed as a potential impact structure. We have studied the structure in detail, but no field or microscopic evidence has been found to support the impact hypothesis

  18. Knottin cyclization: impact on structure and dynamics

    Directory of Open Access Journals (Sweden)

    Gracy Jérôme

    2008-12-01

    Full Text Available Abstract Background Present in various species, the knottins (also referred to as inhibitor cystine knots constitute a group of extremely stable miniproteins with a plethora of biological activities. Owing to their small size and their high stability, knottins are considered as excellent leads or scaffolds in drug design. Two knottin families contain macrocyclic compounds, namely the cyclotides and the squash inhibitors. The cyclotide family nearly exclusively contains head-to-tail cyclized members. On the other hand, the squash family predominantly contains linear members. Head-to-tail cyclization is intuitively expected to improve bioactivities by increasing stability and lowering flexibility as well as sensitivity to proteolytic attack. Results In this paper, we report data on solution structure, thermal stability, and flexibility as inferred from NMR experiments and molecular dynamics simulations of a linear squash inhibitor EETI-II, a circular squash inhibitor MCoTI-II, and a linear analog lin-MCoTI. Strikingly, the head-to-tail linker in cyclic MCoTI-II is by far the most flexible region of all three compounds. Moreover, we show that cyclic and linear squash inhibitors do not display large differences in structure or flexibility in standard conditions, raising the question as to why few squash inhibitors have evolved into cyclic compounds. The simulations revealed however that the cyclization increases resistance to high temperatures by limiting structure unfolding. Conclusion In this work, we show that, in contrast to what could have been intuitively expected, cyclization of squash inhibitors does not provide clear stability or flexibility modification. Overall, our results suggest that, for squash inhibitors in standard conditions, the circularization impact might come from incorporation of an additional loop sequence, that can contribute to the miniprotein specificity and affinity, rather than from an increase in conformational rigidity

  19. Assessment of Containment Structures Against Missile Impact Threats

    Institute of Scientific and Technical Information of China (English)

    LI Q M

    2006-01-01

    In order to ensure the highest safety requirements,nuclear power plant structures (the containment structures,the fuel storages and transportation systems) should be assessed against all possible internal and external impact threats.The internal impact threats include kinetic missiles generated by the failure of high pressure vessels and pipes,the failure of high speed rotating machineries and accidental drops.The external impact threats may come from airborne missiles,aircraft impact,explosion blast and fragments.The impact effects of these threats on concrete and steel structures in a nuclear power plant are discussed.Methods and procedures for the impact assessment of nuclear power plants are introduced.Recent studies on penetration and perforation mechanics as well as progresses on dynamic properties of concrete-like materials are presented to increase the understanding of the impact effects on concrete containment structures.

  20. Chesapeake Bay impact structure: Morphology, crater fill, and relevance for impact structures on Mars

    Science.gov (United States)

    Horton, J.W.; Ormo, J.; Powars, D.S.; Gohn, G.S.

    2006-01-01

    The late Eocene Chesapeake Bay impact structure (CBIS) on the Atlantic margin of Virginia is one of the largest and best-preserved "wet-target" craters on Earth. It provides an accessible analog for studying impact processes in layered and wet targets on volatile-rich planets. The CBIS formed in a layered target of water, weak clastic sediments, and hard crystalline rock. The buried structure consists of a deep, filled central crater, 38 km in width, surrounded by a shallower brim known as the annular trough. The annular trough formed partly by collapse of weak sediments, which expanded the structure to ???85 km in diameter. Such extensive collapse, in addition to excavation processes, can explain the "inverted sombrero" morphology observed at some craters in layered targets. The distribution of crater-fill materials i n the CBIS is related to the morphology. Suevitic breccia, including pre-resurge fallback deposits, is found in the central crater. Impact-modified sediments, formed by fluidization and collapse of water-saturated sand and silt-clay, occur in the annular trough. Allogenic sediment-clast breccia, interpreted as ocean-resurge deposits, overlies the other impactites and covers the entire crater beneath a blanket of postimpact sediments. The formation of chaotic terrains on Mars is attributed to collapse due to the release of volatiles from thick layered deposits. Some flat-floored rimless depressions with chaotic infill in these terrains are impact craters that expanded by collapse farther than expected for similar-sized complex craters in solid targets. Studies of crater materials in the CBIS provide insights into processes of crater expansion on Mars and their links to volatiles. ?? The Meteoritical Society, 2006.

  1. The Impact of Structural Genomics: Expectations and Outcomes

    Energy Technology Data Exchange (ETDEWEB)

    Chandonia, John-Marc; Brenner, Steven E.

    2005-12-21

    Structural Genomics (SG) projects aim to expand our structural knowledge of biological macromolecules, while lowering the average costs of structure determination. We quantitatively analyzed the novelty, cost, and impact of structures solved by SG centers, and contrast these results with traditional structural biology. The first structure from a protein family is particularly important to reveal the fold and ancient relationships to other proteins. In the last year, approximately half of such structures were solved at a SG center rather than in a traditional laboratory. Furthermore, the cost of solving a structure at the most efficient U.S. center has now dropped to one-quarter the estimated cost of solving a structure by traditional methods. However, top structural biology laboratories are much more efficient than the average, and comparable to SG centers despite working on very challenging structures. Moreover, traditional structural biology papers are cited significantly more often, suggesting greater current impact.

  2. Stratigraphic and Structural Characteristics of the Santa Marta Impact Structure, Brazil

    Science.gov (United States)

    Oliveira, G. J. G.; Chamani, M.; Góes, A. M.; Crósta, A. P.; Vasconcelos, M. A. R.; Reimold, W. U.

    2016-08-01

    Santa Marta structure is a moderate-size complex impact structure formed in sedimentary targets, Brazil. We provide an overview of the stratigraphy and deformation patterns of the strata identified within the structure.

  3. Impact Structures: What Does Crater Diameter Mean?

    Science.gov (United States)

    Turtle, E. P.; Pierazzo, E.; Collins, G. S.; Osinski, G. R.; Melosh, H. J.; Morgan, J. V.; Reimold, W. U.; Spray, J. G.

    2004-03-01

    Crater diameter is an important parameter in energy scaling and impact simulations. However, disparate types of data make the use of consistent metrics difficult. We suggest a consistent terminology and discuss it in the context of several examples.

  4. THE MUTUAL IMPACT OF ORGANIZATIONAL CULTURE AND STRUCTURE

    OpenAIRE

    Janićijević Nebojša

    2013-01-01

    This paper explores the relationship between the structure and culture of an organization. The starting assumption is that organizational structure and organizational culture impact each other, and that there is a causal relationship due to which the agreement of the two components of organization leads to better performance. First, the mechanism through which organizational culture impacts the design of organizational structures and the manner in which org...

  5. The two Suvasvesi impact structures, Finland: Argon isotopic evidence for a "false" impact crater doublet

    Science.gov (United States)

    Schmieder, Martin; Schwarz, Winfried H.; Trieloff, Mario; Buchner, Elmar; Hopp, Jens; Tohver, Eric; Pesonen, Lauri J.; Lehtinen, Martti; Moilanen, Jarmo; Werner, Stephanie C.; Öhman, Teemu

    2016-05-01

    The two neighboring Suvasvesi North and South impact structures in central-east Finland have been discussed as a possible impact crater doublet produced by the impact of a binary asteroid. This study presents 40Ar/39Ar geochronologic data for impact melt rocks recovered from the drilling into the center of the Suvasvesi North impact structure and melt rock from glacially transported boulders linked to Suvasvesi South. 40Ar/39Ar step-heating analysis yielded two essentially flat age spectra indicating a Late Cretaceous age of ~85 Ma for the Suvasvesi North melt rock, whereas the Suvasvesi South melt sample gave a Neoproterozoic minimum (alteration) age of ~710 Ma. Although the statistical likelihood for two independent meteorite strikes in close proximity to each other is rather low, the remarkable difference in 40Ar/39Ar ages of >600 Myr for the two Suvasvesi impact melt samples is interpreted as evidence for two temporally separate, but geographically closely spaced, impacts into the Fennoscandian Shield. The Suvasvesi North and South impact structures are, thus, interpreted as a "false" crater doublet, similar to the larger East and West Clearwater Lake impact structures in Québec, Canada, recently shown to be unrelated. Our findings have implications for the reliable recognition of impact crater doublets and the apparent rate of binary asteroid impacts on Earth and other planetary bodies in the inner solar system.

  6. Geophysical and structural criteria for the identification of buried impact structures, with reference to Australia

    Science.gov (United States)

    Glikson, Andrew; Uysal, I. Tonguç

    2013-10-01

    The discovery of large asteroid impact structures, likely and possible impact structures, onshore and offshore the Australian continent (Woodleigh [120 km; ~ 360 Ma], Gnargoo [75 km; Lower Permian — upper Cretaceous], Tookoonooka [55-65 km; ~ 125 Ma], Talundilly [~ 84 km; ~ 125 Ma], Mount Ashmore [> 100 km; end-Eocene] and Warburton twin structures [> 400 km; pre-end Carboniferous]) requires re-examination of the diagnostic criteria used for their identification. Bouguer anomalies of established impact structures (Chicxulub [170 km; 64.98 ± 0.05 Ma], Woodleigh impact structure and Gnargoo probable impact structure display a unique structural architecture where pre-impact structural ridges are intersected and truncated by the outer ring of the circular structure. Seismic reflection data outline circular central uplift domes, basement plugs and rim synclines. Sharp circular seismic tomography anomalies indicate low velocity columns under both the Woodleigh impact structure and Warburton probable impact, hinting at deep crustal fracturing. Deformed, curved and clouded intra-crystalline planar deformation features in quartz (Qz/PDFs), displaying Miller indices ({10-11}, {10-12}, {10-13}) diagnostic of shock metamorphism, abound around exposed established impact structures (Vredefort [298 km; 2023 ± 4 Ma], Sudbury [~ 250 km; 1850 ± 3 Ma], Charlevoix [54 km; 342 ± 15 Ma], Manicouagan [100 km; 214 ± 1 Ma]), Tookoonooka and Talundilly). Deformed Qz/PDFs allow recognition of shock metamorphism in buried impact structures, where original Qz/PDFs were bent, recrystallized and/or clouded during formation of the central uplift and hydrothermal activity triggered by the impact. Planar deformation in quartz can also occur in explosive pyroclastic units but are limited to Boehm lamella (Brazil twins) with single lamella sets {0001}. It has been suggested that a class of microstructures in quartz, referred to as metamorphic deformation lamella (Qz/MDL), occur in endogenic

  7. Impact of Technology on Management Structure

    OpenAIRE

    Glushkov, L.; Razvigorova, E.

    1988-01-01

    The problem of type, characteristics, and factors which influence organizational structure has always been a basic problem in management, both for researchers and for managers. Organizational structure, in addition to being a management tool, is also an expression of power and social status, and this obviously makes it an attractive problem for everyone. In management literature, particularly in the literature on the management of innovation processes, there are few studies more numerous than...

  8. Study of Similarity Law for Bird Impact on Structure

    Institute of Scientific and Technical Information of China (English)

    Li Yulong; Zhang Yongkang; Xue Pu

    2008-01-01

    With dimensional analysis and similarity theory, the model similarity law of aircraft structures under bird impact load is investi-gated. Numerical calculations by means of nonlinear dynamic software ANSYS/LS-DYNA are conducted on the finite element models constructed with different scaling factors. The influence of strain rate on the model similarity law is found to be dependent on the swain rate sensitivity of materials and scale factors. Specifically, materials that are not sensitive to strain rate obey the model similarity law in the bird impact process. The conclusions obtained are supposed to provide a theoretical basis for the experimental work of bird impact on aircraft structure.

  9. Mjolnir structure: An impact crater in the Barents Sea

    Energy Technology Data Exchange (ETDEWEB)

    Dypvik, H.; Gudlaugsson, S.T.; Tsikalas, F.; Faleide, J.I.; Nagy, J. [Univ. of Oslo (Norway); Attrep, M. Jr. [Los Alamos National Lab., NM (United States); Ferrell, R.E. Jr. [Louisiana State Univ., Baton Rouge, LA (United States); Krinsley, D.H. [Univ. of Oregon, Eugene, OR (United States); Mork, A. [IKU Petroleum Research, Trondheim (Norway)

    1996-09-01

    A systematic search for impact indicators was conducted on a core of Late Jurassic-Early Cretaceous sedimentary strata from the vicinity of the proposed Mjolnir impact structure, Barents Sea. A 0.8 m-thick section of the core was found to contain unequivocal indicators of meteoritic impact: shocked quartz grains and a strong enrichment in iridium. The ejecta-bearing strata were discovered only 30 km north-northeast of the structure, within a stratigraphic interval corresponding to the seismically defined deformation event at Mjolnir. Further study of this unusually well presented impact-crater-ejecta-layer pair may help constrain poorly understood aspects of large-magnitude meteorite impacts into the oceans. 14 refs., 4 figs.

  10. Chesapeake Bay impact structure: A blast from the past

    Science.gov (United States)

    Powars, David S.; Edwards, Lucy E.; Gohn, Gregory S.; Horton, Jr., J. Wright

    2015-10-28

    About 35 million years ago, a 2-mile-wide meteorite smashed into Earth in what is now the lower Chesapeake Bay in Virginia. The oceanic impact vaporized, melted, fractured, and displaced rocks and sediments and sent billions of tons of water, sediments, and rocks into the air. Glassy particles of solidified melt rock rained down as far away as Texas and the Caribbean. Large tsunamis affected most of the North Atlantic basin. The resulting impact structure is more than 53 miles wide and has a 23-mile-wide, filled central crater surrounded by collapsed sediments. Now buried by hundreds of feet of younger sediments, the Chesapeake Bay impact structure is among the 20 largest known impact structures on Earth.

  11. Experimental Study of Hypervelocity Impact on Multi-Shock Structure

    Institute of Scientific and Technical Information of China (English)

    张庆明; 陈沿海; 黄风雷

    2004-01-01

    Hypervelocity impact tests on multi-shock shields are carried out in order to develop space structures against space debris impacts. Sheets of LY12 aluminum were used as bumpers. The total thickness of shield structure, which consists of several sheets with various thickness, is 3.0 mm or 2.0 mm. Results of the tests show that the type 0.5 mm+0.5 mm+0.5 mm+0.5 mm is a better choice of spacecraft shield structure.

  12. Examining the factor structure of the Multiple Sclerosis Impact Scale.

    Science.gov (United States)

    Fitzgerald, Shawn M; Li, Jian; Rumrill, Phillip D; Merchant, William; Bishop, Malachy

    2014-01-01

    The purpose of this study was to investigate the factor structure of the Multiple Sclerosis Impact Scale (MSIS-29) to assess its suitability for modeling the impact of MS on a nation-wide sample of individuals from the United States. Investigators completed a Confirmatory Factor Analysis (CFA) to examine the two-factor structure proposed by Hobart et al. [17]. Although the original MSIS-29 factor structure did not fit the data exactly, the hypothesized two-factor model was partially supported in the current data. Implications for future instrument development and rehabilitation practice are discussed.

  13. The mutual impact of organizational culture and structure

    Directory of Open Access Journals (Sweden)

    Janićijević Nebojša

    2013-01-01

    Full Text Available This paper explores the relationship between the structure and culture of an organization. The starting assumption is that organizational structure and organizational culture impact each other, and that there is a causal relationship due to which the agreement of the two components of organization leads to better performance. First, the mechanism through which organizational culture impacts the design of organizational structures and the manner in which organizational structure affects the maintenance, strengthening, or changing of organizational culture is explained at the conceptual level. Then, based on the known classifications of organizational structure and culture, they are put into a relationship of direct mutual interdependence. This is done by generating hypotheses about the agreement of particular types of organizational culture and particular types of organizational structure.

  14. Gravity survey of the Mt. Toondina impact structure, South Australia

    Science.gov (United States)

    Plescia, J. B.; Shoemaker, E. M.; Shoemaker, C. S.

    1991-06-01

    The Mt. Toondina impact structure is located in northern South Australia, about 45 km south of the town of Oodnadatta. Only the central uplift is exposed. The outcrops at Mt. Toondina reveal a remarkable structural anomaly surrounded by a broad expanse of nearly flat-lying beds of the Bulldog Shale of Early Cretaceous age. A gravity survey was undertaken in 1989 to determine the diameter of the impact structure, define the form of the central uplift, and understand the local crustal structure. Data were collected along two orthogonal lines across the structure. In addition to the profiles, a significant number of measurements were made on and around the central uplift. The 1989 gravity data combined with 1963 gravity data and the seismic reflection data provide an excellent data base to interpret the subsurface structure of the Mt. Toondina feature.

  15. Governance structures impact on eHealth

    DEFF Research Database (Denmark)

    Kierkegaard, Patrick

    2015-01-01

    and secondary data sources. All data collection was carried out through desk-research. Data collection relied on performing an extensive search of literature for relevant studies using combinations of keywords that reflected eHealth and governance-related topics. Inclusion and exclusion criteria׳s were applied......Background National eHealth implementation efforts need to move beyond the scope of making technology the primary focus and instead consider the broader spectrum of influences that can either hinder or facilitate eHealth adoption such as governance structures and policies. In this study, Denmark...... serves as an ideal candidate for further examination due to the country׳s rich history of intertwining events that have played an important role in the dynamic relationship between governance and eHealth success and failures. Methods A case study approach was used to gather a combination of primary...

  16. Ash Shutbah: A possible impact structure in Saudi Arabia

    Science.gov (United States)

    Gnos, Edwin; Hofmann, Beda A.; Schmieder, Martin; Al-Wagdani, Khalid; Mahjoub, Ayman; Al-Solami, Abdulaziz A.; Habibullah, Siddiq N.; Matter, Albert; Alwmark, Carl

    2014-10-01

    We have investigated the Ash Shutbah circular structure in central Saudi Arabia (21°37'N 45°39'E) using satellite imagery, field mapping, thin-section petrography, and X-ray diffraction of collected samples. The approximately 2.1 km sized structure located in flat-lying Jurassic Tuwaiq Mountain Limestone has been nearly peneplained by erosional processes. Satellite and structural data show a central area consisting of Dhruma Formation sandstones with steep bedding and tight folds plunging radially outward. Open folding occurs in displaced, younger Tuwaiq Mountain Limestone Formation blocks surrounding the central area, but is absent outside the circular structure. An approximately 60 cm thick, unique folded and disrupted orthoquartzitic sandstone marker bed occurring in the central area of the structure is found 140 m deeper in undisturbed escarpment outcrops located a few hundred meters west of the structure. With exception of a possible concave shatter cone found in the orthoquartzite of the central area, other diagnostic shock features are lacking. Some quartz-rich sandstones from the central area show pervasive fracturing of quartz grains with common concussion fractures. This deformation was followed by an event of quartz dissolution and calcite precipitation consistent with local sea- or groundwater heating. The combination of central stratigraphic uplift of 140 m, concussion features in discolored sandstone, outward-dipping concentric folds in the central area, deformation restricted to the rocks of the ring structure, a complex circular structure of 2.1 km diameter that appears broadly consistent with what one would expect from an impact structure in sedimentary targets, and a possible shatter cone all point to an impact origin of the Ash Shutbah structure. In fact, the Ash Shutbah structure appears to be a textbook example of an eroded, complex impact crater located in flat-lying sedimentary rocks, where the undisturbed stratigraphic section can be

  17. Airborne and impact sound transmission in super-light structures

    DEFF Research Database (Denmark)

    Christensen, Jacob Ellehauge; Hertz, Kristian Dahl; Brunskog, Jonas

    2011-01-01

    Super-light structures are newly invented and based on combining lightweight concrete with normal concrete for lighter structures and better structural performance. The overall principle is based on load carrying arches of a normal concrete stabilised and protected from fire by a light......-aggregate concrete. A super-light deck element is developed. It is intended to be lighter than traditional deck structures without compromising the acoustic performance. It is primarily the airborne sound insulation, which is of interest as the requirements for the impact sound insulation to a higher degree can...

  18. Reconnaissance survey of the Duolun ring structure in Inner Mongolia: Not an impact structure

    Science.gov (United States)

    Xu, Xiaoming; Kenkmann, Thomas; Xiao, Zhiyong; Sturm, Sebastian; Metzger, Nicolai; Yang, Yu; Weimer, Daniela; Krietsch, Hannes; Zhu, Meng-Hua

    2017-09-01

    The Duolun basin, which is located in Inner Mongolia, China, has been proposed to be an impact structure with an apparent rim diameter of about 70, or even 170 km. The designation as an impact structure was based on its nearly circular topography, consisting of an annular moat that surrounds an inner hummocky region, and the widespread occurrences of various igneous rocks, polymict breccias, and deformed crustal rocks. Critical shock metamorphic evidence is not available to support the impact hypothesis. We conducted two independent reconnaissance field surveys to this area and studied the lithology both within and outside of the ring structure. We collected samples from all lithologies that might contain evidence of shock metamorphism as suggested by their locations, especially those sharing similar appearances with impact breccias, suevites, impact melt rocks, and shatter cones. Field investigation, together with thin-section examination, discovered that the suspected impact melt rocks are actually Early Cretaceous and Late Jurassic lava flows and pyroclastic deposits of rhyolitic to trachytic compositions, and the interpreted impact glass is typical volcanic glass. Petrographic analyses of all the samples reveal no indications for shock metamorphic overprint. All these lines of evidence suggest that the Duolun basin was not formed through impact cratering. The structural deformation and spatial distribution pattern of the igneous rocks suggest that the Duolun basin is most likely a Jurassic-Cretaceous complex rhyolite caldera system that has been partly filled with sediments forming an annular basin, followed by resurgent doming of the central area.

  19. Deep drilling in the Chesapeake Bay impact structure - An overview

    Science.gov (United States)

    Gohn, G.S.; Koeberl, C.; Miller, K.G.; Reimold, W.U.

    2009-01-01

    The late Eocene Chesapeake Bay impact structure lies buried at moderate depths below Chesapeake Bay and surrounding landmasses in southeastern Virginia, USA. Numerous characteristics made this impact structure an inviting target for scientific drilling, including the location of the impact on the Eocene continental shelf, its threelayer target structure, its large size (??85 km diameter), its status as the source of the North American tektite strewn field, its temporal association with other late Eocene terrestrial impacts, its documented effects on the regional groundwater system, and its previously unstudied effects on the deep microbial biosphere. The Chesapeake Bay Impact Structure Deep Drilling Project was designed to drill a deep, continuously cored test hole into the central part of the structure. A project workshop, funding proposals, and the acceptance of those proposals occurred during 2003-2005. Initial drilling funds were provided by the International Continental Scientific Drilling Program (ICDP) and the U.S. Geological Survey (USGS). Supplementary funds were provided by the National Aeronautics and Space Administration (NASA) Science Mission Directorate, ICDP, and USGS. Field operations were conducted at Eyreville Farm, Northampton County, Virginia, by Drilling, Observation, and Sampling of the Earth's Continental Crust (DOSECC) and the project staff during September-December 2005, resulting in two continuously cored, deep holes. The USGS and Rutgers University cored a shallow hole to 140 m in April-May 2006 to complete the recovered section from land surface to 1766 m depth. The recovered section consists of 1322 m of crater materials and 444 m of overlying postimpact Eocene to Pleistocene sediments. The crater section consists of, from base to top: basement-derived blocks of crystalline rocks (215 m); a section of suevite, impact melt rock, lithic impact breccia, and cataclasites (154 m); a thin interval of quartz sand and lithic blocks (26 m); a

  20. Structural Damage Prediction and Analysis for Hypervelocity Impact: Consulting

    Science.gov (United States)

    1995-01-01

    A portion of the contract NAS8-38856, 'Structural Damage Prediction and Analysis for Hypervelocity Impacts,' from NASA Marshall Space Flight Center (MSFC), included consulting which was to be documented in the final report. This attachment to the final report contains memos produced as part of that consulting.

  1. Post-impact sedimentation in the Ritland impact structure, Southwestern Norway

    OpenAIRE

    Tomczyk, Michal

    2010-01-01

    A succession of crater infill sediments is preserved within the Ritland impact structure. Ritland is good example of a small depositional basin where a range of processes from debris flows to turbiditic currents and finally suspension fall-out took place within a very restricted area. Immediately after impact slumps/slides, and mass flows dominated, later to be replaced by running water activities in much calmer basin environment, like fine-grained sedimentation. The sedimentary successions o...

  2. Structure and Dynamics of Coauthorship, Citation, and Impact within CSCW

    CERN Document Server

    Keegan, Brian; Finholt, Thomas A; Kaye, Joseph "Jofish"

    2013-01-01

    CSCW has stabilized as an interdisciplinary venue for computer, information, cognitive, and social scientists but has also undergone significant changes in its format in recent years. This paper uses methods from social network analysis and bibliometrics to re-examine the structures of CSCW a decade after its last systematic analysis. Using data from the ACM Digital Library, we analyze changes in structures of coauthorship and citation between 1986 and 2013. Statistical models reveal significant but distinct patterns between papers and authors in how brokerage and closure in these networks affects impact as measured by citations and downloads. Specifically, impact is unduly influenced by structural position, such that ideas introduced by those in the core of the CSCW community (e.g., elite researchers) are advantaged over those introduced by peripheral participants (e.g., newcomers). This finding is examined in the context of recent changes to the CSCW conference that may have the effect of upsetting the pref...

  3. Guard Ring Width Impact on Impact Parameter Performances and Structure Simulations

    CERN Document Server

    Gouldwell, A; Rahman, M; Bates, R; Wemyss, M; Murphy, G; Turner, P; Biagi, S F

    2003-01-01

    The 1 mm guard ring structure of the VELO sensors has been simulated. The performance of the baseline design is considered and a design which improves the electric field characteristics proposed. Designs which would permit a reduced guard ring width, to 0.5 mm or better, are also discussed and shown to also have similarly good electric field performances. The effect of implementing these designs on the impact parameter resolution of LHCb is found to be better than 5 %. This design is currently being fabricated. Finally, a very different structure, the trench guard ring, is considered which would then allow an impact parameter resolution improvement of approximately 7 %.

  4. Analysis of Dynamic Properties of Piezoelectric Structure under Impact Load

    Directory of Open Access Journals (Sweden)

    Taotao Zhang

    2015-10-01

    Full Text Available An analytical model of the dynamic properties is established for a piezoelectric structure under impact load, without considering noise and perturbations in this paper. Based on the general theory of piezo-elasticity and impact mechanics, the theoretical solutions of the mechanical and electrical fields of the smart structure are obtained with the standing and traveling wave methods, respectively. The comparisons between the two methods have shown that the standing wave method is better for studying long-time response after an impact load. In addition, good agreements are found between the theoretical and the numerical results. To simulate the impact load, both triangle and step pulse loads are used and comparisons are given. Furthermore, the influence of several parameters is discussed so as to provide some advices for practical use. It can be seen that the proposed analytical model would benefit, to some extent, the design and application (especially the airport runway of the related smart devices by taking into account their impact load performance.

  5. High Energy Wide Area Blunt Impact on Composite Aircraft Structures

    Science.gov (United States)

    DeFrancisci, Gabriela K.

    The largest source of damage to commercial aircraft is caused by accidental contact with ground service equipment (GSE). The cylindrical bumper typically found on GSE distributes the impact load over a large contact area, possibly spanning multiple internal structural elements (frame bays) of a stiffened-skin fuselage. This type of impact can lead to damage that is widespread and difficult to detect visually. To address this problem, monolithic composite panels of various size and complexity have been modeled and tested quasi-statically and dynamically. The experimental observations have established that detectability is dependent on the impact location and immediately-adjacent internal structure of the panel, as well as the impactor geometry and total deformation of the panel. A methodology to model and predict damage caused by wide area blunt impact events was established, which was then applied to more general cases that were not tested in order to better understand the nature of this type of impact event and how it relates to the final damage state and visual detectability.

  6. The complex impact structure Serra da Cangalha, Tocantins State, Brazil

    Science.gov (United States)

    Kenkmann, Thomas; Vasconcelos, Marcos A. R.; Crósta, Alvaro P.; Reimold, Wolf U.

    2011-06-01

    Serra da Cangalha is a complex impact structure with a crater diameter of 13,700 m and a central uplift diameter of 5800 m. New findings of shatter cones, planar fractures, feather features, and possible planar deformation features are presented. Several ring-like features that are visible on remote sensing imagery are caused by selective erosion of tilted strata. The target at Serra da Cangalha is composed of Devonian to Permian sedimentary rocks, mainly sandstones that are interlayered with siltstone and claystones. NNE-SSW and WNW-ESE-striking joint sets were present prior to the impact and also overprinted the structure after its formation. As preferred zones of weakness, these joint sets partly controlled the shape of the outer perimeter of the structure and, in particular, affected the deformation within the central uplift. Joints in radial orientation to the impact center did not undergo a change in orientation during tilting of strata when the central uplift was formed. These planes were used as major displacement zones. The asymmetry of the central uplift, with preferred overturning of strata in the northern to western sector, may suggest a moderately oblique impact from a southerly direction. Buckle folding of tilted strata, as well as strata overturning, indicates that the central uplift became gravitationally unstable at the end of crater formation.

  7. Impact of Financial Structure on the Cost of Solar Energy

    Energy Technology Data Exchange (ETDEWEB)

    Mendelsohn, M.; Kreycik, C.; Bird, L.; Schwabe, P.; Cory, K.

    2012-03-01

    To stimulate investment in renewable energy generation projects, the federal government developed a series of support structures that reduce taxes for eligible investors--the investment tax credit, the production tax credit, and accelerated depreciation. The nature of these tax incentives often requires an outside investor and a complex financial arrangement to allocate risk and reward among the parties. These financial arrangements are generally categorized as 'advanced financial structures.' Among renewable energy technologies, advanced financial structures were first widely deployed by the wind industry and are now being explored by the solar industry to support significant scale-up in project development. This report describes four of the most prevalent financial structures used by the renewable sector and evaluates the impact of financial structure on energy costs for utility-scale solar projects that use photovoltaic and concentrating solar power technologies.

  8. The Impact of Tourism on the Sociocultural Structure of Cyprus

    OpenAIRE

    Spanou, Elena

    2006-01-01

    This paper is based on evaluating tourism development in Cyprus, a European nation, and its impacts on the socio-cultural structure of the island. The principal concern of this research is aid in sustaining the resource base on which the tourism development in Cyprus depends on. The paper concludes that in spite of all the negative and positive impacts of tourism on Cyprus it is not yet clear whether the benefits outweigh the costs. The reason for this uncertainty is that most of the research...

  9. Impact craters as biospheric microenvironments, Lawn Hill Structure, Northern Australia.

    Science.gov (United States)

    Lindsay, John; Brasier, Martin

    2006-04-01

    Impact craters on Mars act as traps for eolian sediment and in the past may have provided suitable microenvironments that could have supported and preserved a stressed biosphere. If this is so, terrestrial impact structures such as the 18-km-diameter Lawn Hill Structure, in northern Australia, may prove useful as martian analogs. We sampled outcrop and drill core from the carbonate fill of the Lawn Hill Structure and recorded its gamma-log signature. Facies data along with whole rock geochemistry and stable isotope signatures show that the crater fill is an outlier of the Georgina Basin and was formed by impact at, or shortly before, approximately 509-506 million years ago. Subsequently, it was rapidly engulfed by the Middle Cambrian marine transgression, which filled it with shallow marine carbonates and evaporites. The crater formed a protected but restricted microenvironment in which sediments four times the thickness of the nearby basinal succession accumulated. Similar structures, common on the martian surface, may well have acted as biospheric refuges as the planet's water resources declined. Low-pH aqueous environments on Earth similar to those on Mars, while extreme, support diverse ecologies. The architecture of the eolian crater fill would have been defined by long-term ground water cycles resulting from intermittent precipitation in an extremely arid climate. Nutrient recycling, critical to a closed lacustrine sub-ice biosphere, could be provided by eolian transport onto the frozen water surface.

  10. Impact of the Ownership Structure on Corporate Management in Engineering

    Directory of Open Access Journals (Sweden)

    Dieieva Nataliia E.

    2014-02-01

    Full Text Available The article analyses impact of the ownership structure on corporate management in the engineering industry of Ukraine. In order to detect impact of the structure of corporate ownership on corporate management the article uses general scientific and special methods of study: method of critical analysis and generalisation of theoretical studies, comparison method and statistical method. Analysis of engineering enterprises confirmed availability of impact of the structure of corporate ownership on corporate management. The article also shows that the engineering industry of Ukraine is characterised with the concentrated ownership structure, which has the following features: restriction of rights of minority shareholders with respect to management and control in a joint stock company; availability of corporate conflicts between majority and minority shareholders; availability of intense control of owners over management, which influences efficiency of making managerial decisions; hired managers and enterprise employees have no possibility to acquire stock of a joint stock company including in the form of bonuses and incentives; the controlling owner is interested in efficient activity of the enterprise and tries to create necessary conditions for this. The conducted studies give a possibility to establish that a share of stock that belongs to a hired executive body is smaller in those joint stock companies in which concentration of ownership is higher. The article also shows that the higher ownership concentration the higher is the probability that the owner would be a part of controlling bodies.

  11. Shock barometry of the Siljan impact structure, Sweden

    Science.gov (United States)

    Holm, Sanna; Alwmark, Carl; Alvarez, Walter; Schmitz, Birger

    2011-12-01

    The Siljan impact structure in Sweden is the largest confirmed impact structure in Western Europe. Despite this, the structure has been poorly studied in the past, and detailed studies of shock metamorphic features in the target lithologies are missing. Here, we present the results of a detailed systematic search for shock metamorphic features in quartz grains from 73 sampled localities at Siljan. At 21 localities from an area approximately 20 km in diameter located centrally in the structure, the orientations of 2851 planar deformation feature sets in 1179 quartz grains were measured. Observations of shatter cones outside of the zone with shocked quartz extend the total shocked area to approximately 30 km in diameter. The most strongly shocked samples, recording pressures of up to 20 GPa, occur at the very central part of the structure, and locally in these samples, higher pressures causing melting conditions in the affected rocks were reached. Pressures recorded in the studied samples decrease outwards from the center of the structure, forming roughly circular envelopes around the proposed shock center. Based on the distribution pattern of shocked quartz at Siljan, the original transient cavity can be estimated at approximately 32-38 km in diameter. After correcting for erosion, we conclude that the original rim to rim diameter of the Siljan crater was somewhere in the size range 50-90 km.

  12. Strategic Planning Process and Organizational Structure: Impacts, Confluence and Similarities

    Directory of Open Access Journals (Sweden)

    Dyogo Felype Neis

    2017-01-01

    Full Text Available This article aims to analyze the relationship between the strategic planning process and organizational structure in the reality of a complex organization: the Public Prosecutor’s Office of Santa Catarina (MPSC. The research is set by the single case study research strategy and data were collected through the following instruments: bibliographical research, documentary research, semi-structured interviews and systematic observation. The conclusion indicates that the phases of the strategic planning process influence and are influenced by the elements of the organizational structure and highlights the confluences, the impacts and similarities between the stages of formulation and implementation of the strategic process with the various constituent elements of the organizational structure.

  13. Grid faults' impact on wind turbine structural loads

    DEFF Research Database (Denmark)

    Hansen, Anca D.; Cutululis, A. Nicolaos; Iov, Florin;

    2007-01-01

    The objective of this work is to illustrate the impact of the grid faults on the wind turbine structural loads. Grid faults are typically simulated in detailed power system simulation tools, which by applying simplified mechanical models, are not able to provide a throughout insight...... on the structural loads caused by sudden disturbances on the grid. On the other hand, structural loads of the wind turbine are typically assessed in advanced aerolastic computer codes, which by applying simplified electrical models do not provide detailed electrical insight. This paper presents a simulation...... of the wind turbine during grid faults. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator....

  14. Impact origin of the Sudbury structure: Evolution of a theory

    Science.gov (United States)

    Lowman, Paul D., Jr.

    1992-01-01

    This paper reviews the origin, development, and present status of the widely accepted theory, proposed by Robert S. Dietz in 1962, that the Sudbury structure was formed by meteoritic or asteroidal impact. The impact theory for the origin of the Sudbury structure seems supported by a nearly conclusive body of evidence. However, even assuming an impact origin to be correct, at least three major questions require further study: (1) the original size and shape of the crater, before tectonic deformation and erosion; (2) the source of the melt now forming the Sudbury Igneous Complex; and (3) the degree, if any, to which the Ni-Cu-platinum group elements are meteoritic. The history of the impact theory illustrates several under-appreciated aspects of scientific research: (1) the importance of cross-fertilization between space research and terrestrial geology; (2) the role of the outsider in stimulating thinking by insiders; (3) the value of small science, at least in the initial stages of an investigation, Dietz's first field work having been at his own expense; and (4) the value of analogies (here, between the Sudbury Igneous Complex and the maria), which although incorrect in major aspects, may trigger research on totally new lines. Finally, the Sudbury story illustrates the totally unpredictable and, by implication, unplannable nature of basic research, in that insight to the origin of the world's then-greatest Ni deposit came from the study of tektites and the Moon.

  15. Impact of active controls technology on structural integrity

    Science.gov (United States)

    Noll, Thomas; Austin, Edward; Donley, Shawn; Graham, George; Harris, Terry

    1991-01-01

    This paper summarizes the findings of The Technical Cooperation Program to assess the impact of active controls technology on the structural integrity of aeronautical vehicles and to evaluate the present state-of-the-art for predicting the loads caused by a flight-control system modification and the resulting change in the fatigue life of the flight vehicle. The potential for active controls to adversely affect structural integrity is described, and load predictions obtained using two state-of-the-art analytical methods are given.

  16. The impact of structural genomics: the first quindecennial.

    Science.gov (United States)

    Grabowski, Marek; Niedzialkowska, Ewa; Zimmerman, Matthew D; Minor, Wladek

    2016-03-01

    The period 2000-2015 brought the advent of high-throughput approaches to protein structure determination. With the overall funding on the order of $2 billion (in 2010 dollars), the structural genomics (SG) consortia established worldwide have developed pipelines for target selection, protein production, sample preparation, crystallization, and structure determination by X-ray crystallography and NMR. These efforts resulted in the determination of over 13,500 protein structures, mostly from unique protein families, and increased the structural coverage of the expanding protein universe. SG programs contributed over 4400 publications to the scientific literature. The NIH-funded Protein Structure Initiatives alone have produced over 2000 scientific publications, which to date have attracted more than 93,000 citations. Software and database developments that were necessary to handle high-throughput structure determination workflows have led to structures of better quality and improved integrity of the associated data. Organized and accessible data have a positive impact on the reproducibility of scientific experiments. Most of the experimental data generated by the SG centers are freely available to the community and has been utilized by scientists in various fields of research. SG projects have created, improved, streamlined, and validated many protocols for protein production and crystallization, data collection, and functional analysis, significantly benefiting biological and biomedical research.

  17. Grid faults' impact on wind turbine structural loads

    DEFF Research Database (Denmark)

    Hansen, Anca D.; Cutululis, A. Nicolaos; Iov, Florin

    2007-01-01

    The objective of this work is to illustrate the impact of the grid faults on the wind turbine structural loads. Grid faults are typically simulated in detailed power system simulation tools, which by applying simplified mechanical models, are not able to provide a throughout insight on the struct......The objective of this work is to illustrate the impact of the grid faults on the wind turbine structural loads. Grid faults are typically simulated in detailed power system simulation tools, which by applying simplified mechanical models, are not able to provide a throughout insight...... on the structural loads caused by sudden disturbances on the grid. On the other hand, structural loads of the wind turbine are typically assessed in advanced aerolastic computer codes, which by applying simplified electrical models do not provide detailed electrical insight. This paper presents a simulation...... strategy, where the focus is on how to access a proper combination of two complimentary simulations tools, such as the advanced aeroelastic computer code HAWC2 and the detailed power system simulation tool DIgSILENT, in order to provide a whole overview of both the structural and the electrical behaviour...

  18. Noise Impact on European Sea Bass Behavior: Temporal Structure Matters.

    Science.gov (United States)

    Neo, Yik Yaw; Seitz, Johanna; Kastelein, Ronald A; Winter, Hendrik V; Cate, Carel Ten; Slabbekoorn, Hans

    2016-01-01

    Anthropogenic sounds come in different forms, varying not only in amplitude and frequency spectrum but also in temporal structure. Although fish are sensitive to the temporal characteristics of sound, little is known about how their behavior is affected by anthropogenic sounds of different temporal patterns. We investigated this question using groups of Dicentrarchus labrax (European sea bass) in an outdoor basin. Our data revealed that the temporal pattern of sound exposure is important in noise impact assessments.

  19. Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures

    Science.gov (United States)

    French, Bevan M.

    1998-01-01

    This handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures emphasizes terrestrial impact structures, field geology, and particularly the recognition and petrographic study of shock-metamorphic effects in terrestrial rocks. Individual chapters include: 1) Landscapes with Craters: Meteorite Impacts, Earth, and the Solar System; 2) Target Earth: Present, Past and Future; 3) Formation of Impact Craters; 4) Shock-Metamorphic Effects in Rocks and Minerals; 5) Shock-Metamorphosed Rocks (Impactities) in Impact Structures; 6) Impact Melts; 7) How to Find Impact Structures; and 8) What Next? Current Problems and Future Investigations.

  20. Fluid-Structure Interaction in a Fluid-Filled Composite Structure Subjected to Low Velocity Impact

    Science.gov (United States)

    2016-06-01

    this study of impact force, deflection, and strain were measured in a carbon fiber reinforced polymer (CFRP) composite cylinder subjected to low...Sanchez, J. Lopez-Puente, and D. Varas, “On the influence of filling level in CFRP aircraft fuel tank subjected to high velocity impacts,” Composite ...and back sides. The baffle provided the greatest strain reduction at the high fill levels. 14. SUBJECT TERMS glass fiber composite , fluid structure

  1. Impact melt rocks from the Ries structure, Germany: an origin as impact melt flows?

    Science.gov (United States)

    Osinski, Gordon R.

    2004-10-01

    The production of impact melt rocks and glasses is a characteristic feature of hypervelocity impact events on Earth and other planetary bodies. This investigation represents the first detailed study of an unusual series of coherent impact melt rocks intermittently exposed around the periphery of the ~24-km diameter, ~14.5 Ma Ries impact structure, Germany. Optical and analytical scanning electron microscopy (SEM) reveals that the groundmass comprises sanidine, plagioclase, quartz and ilmenite (decreasing order of abundance) with the interstices filled by either fresh or devitrified glassy mesostasis. Primary crystallites display skeletal, dendritic and/or spherulitic textures indicating rapid crystallization from a melt. The mesostasis is characterized by extreme chemical heterogeneity (e.g., FeO and Al 2O 3 contents from ~1 to ~62-80 wt.%). This is likely due to a combination of crystal-liquid fractionation during rapid cooling and crystallization of an originally incompletely homogenized melt. Vapor phase crystallization of sanidine and cristobalite occurred in miarolitic cavities during late-stage cooling of the impact melts. The most likely protolith for the impact melt rocks are granitic rocks present in the crystalline basement target. The high volatile content of the mesostasis suggests that a large volatile component was retained from this protolith. Field observations together with analytical data and micro-textures indicate that the Ries impact melt rocks were molten at the time of, and after, deposition. Field relations with other impactites also suggest that these rocks were emplaced subsequent to the excavation stage of crater formation and that they are not, therefore, ballistic ejecta. Thus, it is proposed that the Ries impact melt rocks were emplaced as ground-hugging impact melt flows that emanated from different regions of the evolving transient cavity during the modification stage of crater formation. This is consistent with, and in fact

  2. Computational modeling and impact analysis of textile composite structures

    Science.gov (United States)

    Hur, Hae-Kyu

    This study is devoted to the development of an integrated numerical modeling enabling one to investigate the static and the dynamic behaviors and failures of 2-D textile composite as well as 3-D orthogonal woven composite structures weakened by cracks and subjected to static-, impact- and ballistic-type loads. As more complicated modeling about textile composite structures is introduced, some of homogenization schemes, geometrical modeling and crack propagations become more difficult problems to solve. To overcome these problems, this study presents effective mesh-generation schemes, homogenization modeling based on a repeating unit cell and sinusoidal functions, and also a cohesive element to study micro-crack shapes. This proposed research has two: (1) studying behavior of textile composites under static loads, (2) studying dynamic responses of these textile composite structures subjected to the transient/ballistic loading. In the first part, efficient homogenization schemes are suggested to show the influence of textile architectures on mechanical characteristics considering the micro modeling of repeating unit cell. Furthermore, the structures of multi-layered or multi-phase composites combined with different laminar such as a sub-laminate, are considered to find the mechanical characteristics. A simple progressive failure mechanism for the textile composites is also presented. In the second part, this study focuses on three main phenomena to solve the dynamic problems: micro-crack shapes, textile architectures and textile effective moduli. To obtain a good solutions of the dynamic problems, this research attempts to use four approaches: (I) determination of governing equations via a three-level hierarchy: micro-mechanical unit cell analysis, layer-wise analysis accounting for transverse strains and stresses, and structural analysis based on anisotropic plate layers, (II) development of an efficient computational approach enabling one to perform transient

  3. Geochemical Comparison of Four Cores from the Manson Impact Structure

    Science.gov (United States)

    Korotev, Randy L.; Rockow, Kaylynn M.; Jolliff, Bradley L.; Haskin, Larry A.; McCarville, Peter; Crossey, Laura J.

    1996-01-01

    Concentrations of 33 elements were determined in relatively unaltered, matrix-rich samples of impact breccia at approximately 3-m-depth intervals in the M-1 core from the Manson impact structure, Iowa. In addition, 46 matrix-rich samples from visibly altered regions of the M-7, M-8, and M-10 cores were studied, along with 42 small clasts from all four cores. Major element compositions were determined for a subset of impact breccias from the M-1 core, including matrix-rich impact-melt breccia. Major- and trace-element compositions were also determined for a suite of likely target rocks. In the M-1 core, different breccia units identified from lithologic examination of cores are compositionally distinct. There is a sharp compositional discontinuity at the boundary between the Keweenawan-shale-clast breccia and the underlying unit of impact-melt breccia (IMB) for most elements, suggesting minimal physical mixing between the two units during emplacement. Samples from the 40-m-thick IMB (M-1) are all similar to each other in composition, although there are slight increases in concentration with depth for those elements that have high concentrations in the underlying fragmental-matrix suevite breccia (SB) (e.g., Na, Ca, Fe, Sc), presumably as a result of greater clast proportions at the bottom margin of the unit of impact-melt breccia. The high degree of compositional similarity we observe in the impact-melt breccias supports the interpretation that the matrix of this unit represents impact melt. That our analyses show such compositional similarity results in part from our technique for sampling these breccias: for each sample we analyzed a few small fragments (total mass: approximately 200 mg) selected to be relatively free of large clasts and visible signs of alteration instead of subsamples of powders prepared from a large mass of breccia. The mean composition of the matrix-rich part of impact-melt breccia from the M-1 core can be modeled as a mixture of approximately

  4. Hydrocode modeling of the Sierra Madera impact structure

    Science.gov (United States)

    Goldin, Tamara J.; Wünnemann, Kai; Melosh, H. Jay; Collins, Gareth S.

    We present the first hydrocode simulations of the formation of the Sierra Madera structure (west Texas, USA), which was caused by an impact into a thick sedimentary target sequence. We modeled Sierra Madera using the iSALE hydrocode, and here we present two best-fit models: 1) a crater with a rim (final crater) diameter of ˜12 km, in agreement with previous authors' interpretations of the original structure, and 2) a crater ˜16 km in diameter with increased postimpact erosion. Both models fit some of the geologic observational data, but discrepancies with estimates of peak shock pressure, extent of deformation, and stratigraphic displacement remain. This study suggests that Sierra Madera may be a larger crater than previously reported and illustrates some of the challenges in simulating impact deformation of sedimentary lithologies. As many terrestrial craters possess some amount of sedimentary rocks in the target sequence, numerical models of impacts into sedimentary targets are essential to our understanding of target rock deformation and the mechanics of crater formation.

  5. Chesapeake Bay Impact Structure Deep Drilling Project Completes Coring

    Directory of Open Access Journals (Sweden)

    the Scientific Staff of the Chesapeake Bay Impact Structure Deep Drilling Project

    2006-09-01

    Full Text Available The Chesapeake Bay Impact Structure Deep Drilling Project (CBIS Project completed its coring operations during September–December 2005 and April–May 2006. Cores were collected continuously to a total depth of 1766 m. The recovered section consists of 1322 m of impactites beneath 444 m of post-impact continental shelf sediments.The CBIS Project is a joint venture of the International Continental Scientifi c Drilling Program (ICDP and the U.S. Geological Survey (USGS. Project activities began with a planning workshop in September 2003 attended by sixtythree scientists from ten countries. Field operations began with site preparation in July 2005, and coring began in September 2005. Drilling, Observation and Sampling of theEarth’s Continental Crust (DOSECC was the general contractor for the drilling operations throughout 2005.

  6. Progressive deformation of feldspar recording low-barometry impact processes, Tenoumer impact structure, Mauritania

    Science.gov (United States)

    Jaret, Steven J.; Kah, Linda C.; Harris, R. Scott

    2014-06-01

    The Tenoumer impact structure is a small, well-preserved crater within Archean to Paleoproterozoic amphibolite, gneiss, and granite of the Reguibat Shield, north-central Mauritania. The structure is surrounded by a thin ejecta blanket of crystalline blocks (granitic gneiss, granite, and amphibolite) and impact-melt rocks. Evidence of shock metamorphism of quartz, most notably planar deformation features (PDFs), occurs exclusively in granitic clasts entrained within small bodies of polymict, glass-rich breccia. Impact-related deformation features in oligoclase and microcline grains, on the other hand, occur both within clasts in melt-breccia deposits, where they co-occur with quartz PDFs, and also within melt-free crystalline ejecta, in the absence of co-occurring quartz PDFs. Feldspar deformation features include multiple orientations of PDFs, enhanced optical relief of grain components, selective disordering of alternate twins, inclined lamellae within alternate twins, and combinations of these individual textures. The distribution of shock features in quartz and feldspar suggests that deformation textures within feldspar can record a wide range of average pressures, starting below that required for shock deformation of quartz. We suggest that experimental analysis of feldspar behavior, combined with detailed mapping of shock metamorphism of feldspar in natural systems, may provide critical data to constrain energy dissipation within impact regimes that experienced low average shock pressures.

  7. Experimental alteration of artificial and natural impact melt rock from the Chesapeake Bay impact structure

    Science.gov (United States)

    Declercq, J.; Dypvik, H.; Aagaard, P.; Jahren, J.; Ferrell, R.E.; Horton, J. Wright

    2009-01-01

    The alteration or transformation of impact melt rock to clay minerals, particularly smectite, has been recognized in several impact structures (e.g., Ries, Chicxulub, Mj??lnir). We studied the experimental alteration of two natural impact melt rocks from suevite clasts that were recovered from drill cores into the Chesapeake Bay impact structure and two synthetic glasses. These experiments were conducted at hydrothermal temperature (265 ??C) in order to reproduce conditions found in meltbearing deposits in the first thousand years after deposition. The experimental results were compared to geochemical modeling (PHREEQC) of the same alteration and to original mineral assemblages in the natural melt rock samples. In the alteration experiments, clay minerals formed on the surfaces of the melt particles and as fine-grained suspended material. Authigenic expanding clay minerals (saponite and Ca-smectite) and vermiculite/chlorite (clinochlore) were identified in addition to analcime. Ferripyrophyllite was formed in three of four experiments. Comparable minerals were predicted in the PHREEQC modeling. A comparison between the phases formed in our experiments and those in the cores suggests that the natural alteration occurred under hydrothermal conditions similar to those reproduced in the experiment. ?? 2009 The Geological Society of America.

  8. Impact of constrained rewiring on network structure and node dynamics.

    Science.gov (United States)

    Rattana, P; Berthouze, L; Kiss, I Z

    2014-11-01

    In this paper, we study an adaptive spatial network. We consider a susceptible-infected-susceptible (SIS) epidemic on the network, with a link or contact rewiring process constrained by spatial proximity. In particular, we assume that susceptible nodes break links with infected nodes independently of distance and reconnect at random to susceptible nodes available within a given radius. By systematically manipulating this radius we investigate the impact of rewiring on the structure of the network and characteristics of the epidemic. We adopt a step-by-step approach whereby we first study the impact of rewiring on the network structure in the absence of an epidemic, then with nodes assigned a disease status but without disease dynamics, and finally running network and epidemic dynamics simultaneously. In the case of no labeling and no epidemic dynamics, we provide both analytic and semianalytic formulas for the value of clustering achieved in the network. Our results also show that the rewiring radius and the network's initial structure have a pronounced effect on the endemic equilibrium, with increasingly large rewiring radiuses yielding smaller disease prevalence.

  9. Low temperature impact testing of welded structural wrought iron

    Science.gov (United States)

    Rogers, Zachary

    During the second half of the 19th century, structural wrought iron was commonly used in construction of bridges and other structures. Today, these remaining structures are still actively in use and may fall under the protection of historic preservation agencies. Continued use and protection leads to the need for inspection, maintenance, and repair of the wrought iron within these structures. Welding can be useful to achieve the appropriate repair, rehabilitation, or replacement of wrought iron members. There is currently very little published on modern welding techniques for historic wrought iron. There is also no pre-qualified method for this welding. The demand for welding in the repair of historic structural wrought iron has led to a line of research investigating shielded metal arc welding (SMAW) of historic wrought iron at the University of Colorado Denver. This prior research selected the weld type and other weld specifications to try and achieve a recognized specific welding procedure using modern SMAW technology and techniques. This thesis continues investigating SMAW of historic wrought iron. Specifically, this thesis addresses the toughness of these welds from analysis of the data collected from performing Charpy V-Notch (CVN) Impact Tests. Temperature was varied to observe the material response of the welds at low temperature. The wrought iron used in testing was from a historic vehicle bridge in Minnesota, USA. This area, and many other areas with wrought iron structures, can experience sustained or fluctuating temperatures far below freezing. Investigating the toughness of welds in historic wrought iron at these temperatures is necessary to fully understand material responses of the existing structures in need of maintenance and repair. It was shown that welded wrought iron is tougher and more ductile than non-welded wrought iron. In regards to toughness, welding is an acceptable repair method. Information on wrought iron, low temperature failure

  10. Structural Intensity Characterization of Composite Laminates Subjected to Impact Load

    Institute of Scientific and Technical Information of China (English)

    WANG Dong-fang; HE Peng-fei; LIU Zi-shun

    2008-01-01

    Structural intensity (SI) characterization of composite laminates subjected to impact load was dis-cussed. The SI pattern of the laminates which have different fiber orientations and boundary conditions wasanalyzed. The resultant forces and velocities of the laminates were calculated, and the structural intensity wasevaluated. The SI streamlines of carbon fiber reinforced epoxy composite laminates and the steel plates werediscussed. The results show that the SI streamlines of the graphite/epoxy laminates are different from that ofthe steel plates, and the SI streamlines are influenced by the boundaries, the stacking sequence of the compositelaminates. The change of the historical central displacement of the graphite/epoxy laminates is fasten thanthat of the steel plates.

  11. Impact of methionine oxidation on calmodulin structural dynamics

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, Megan R.; Thompson, Andrew R.; Nitu, Florentin [Biochemistry, Molecular Biology and Biophysics Department, University of Minnesota, Minneapolis, MN 55455 (United States); Moen, Rebecca J. [Chemistry and Geology Department, Minnesota State University, Mankato, MN 56001 (United States); Olenek, Michael J. [Biology Department, University of Wisconsin, La Crosse, WI 54601 (United States); Klein, Jennifer C., E-mail: jklein@uwlax.edu [Biology Department, University of Wisconsin, La Crosse, WI 54601 (United States); Thomas, David D., E-mail: ddt@umn.edu [Biochemistry, Molecular Biology and Biophysics Department, University of Minnesota, Minneapolis, MN 55455 (United States)

    2015-01-09

    Highlights: • We measured the distance distribution between two spin labels on calmodulin by DEER. • Two structural states, open and closed, were resolved at both low and high Ca. • Ca shifted the equilibrium toward the open state by a factor of 13. • Methionine oxidation, simulated by glutamine substitution, decreased the Ca effect. • These results have important implications for aging in muscle and other tissues. - Abstract: We have used electron paramagnetic resonance (EPR) to examine the structural impact of oxidizing specific methionine (M) side chains in calmodulin (CaM). It has been shown that oxidation of either M109 or M124 in CaM diminishes CaM regulation of the muscle calcium release channel, the ryanodine receptor (RyR), and that mutation of M to Q (glutamine) in either case produces functional effects identical to those of oxidation. Here we have used site-directed spin labeling and double electron–electron resonance (DEER), a pulsed EPR technique that measures distances between spin labels, to characterize the structural changes resulting from these mutations. Spin labels were attached to a pair of introduced cysteine residues, one in the C-lobe (T117C) and one in the N-lobe (T34C) of CaM, and DEER was used to determine the distribution of interspin distances. Ca binding induced a large increase in the mean distance, in concert with previous X-ray crystallography and NMR data, showing a closed structure in the absence of Ca and an open structure in the presence of Ca. DEER revealed additional information about CaM’s structural heterogeneity in solution: in both the presence and absence of Ca, CaM populates both structural states, one with probes separated by ∼4 nm (closed) and another at ∼6 nm (open). Ca shifts the structural equilibrium constant toward the open state by a factor of 13. DEER reveals the distribution of interprobe distances, showing that each of these states is itself partially disordered, with the width of each

  12. Impact of structural heterogeneity in solar absorber layers (Conference Presentation)

    Science.gov (United States)

    Toney, Michael

    2016-09-01

    Impact of structural heterogeneity in solar absorber layers Michael F Toney SLAC National Accelerator Laboratory Structural and morphological heterogeneity is common in thin film and emerging solar cell absorber layers, including organic photovoltaic bulk heterojunctions (OPV BHJs), hybrid organic-inorganic perovskites (HOIP), and Cu2ZnSn(S,Se)4 (CZTSSe), and has a significant impact on the (opto)electronic heterogeneity and hence absorber properties. In this talk I will use X-ray based methods, including scattering and spectroscopies, to characterize and quantify the heterogeneity in OPV BHJs and HOIP absorber layers. The BHJ films are blends of the small molecule X2 and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) where it has been established that there are three distinct region of the films - pure PC71BM, pure X2 and intimately mixed X2:PC71BM. This talk will show how the absolute concentration of the mixed phase can be used to explain the large PC71BM:X2 composition range where good performance is observed [1]. The talk will also show that spin cast CH3NH3PbI3 films consistent of both crystalline and amorphous regions, which can explain previous heterogeneity in the PL imaging [2]. [1] Huang et al., Adv. Energy Mater. 4, 1301886 (2014). [2] deQuilettes et al., Science 348, 683 (2015).

  13. Impact of Methionine Oxidation on Calmodulin Structural Dynamics

    Science.gov (United States)

    McCarthy, Megan R.; Thompson, Andrew R.; Nitu, Florentin; Moen, Rebecca J.; Olenek, Michael J.; Klein, Jennifer C.; Thomas, David D.

    2014-01-01

    We have used electron paramagnetic resonance (EPR) to examine the structural impact of oxidizing specific methionine (M) side chains in calmodulin (CaM). It has been shown that oxidation of either M109 or M124 in CaM diminishes CaM regulation of the muscle calcium release channel, the ryanodine receptor (RyR), and that mutation of M to Q (glutamine) in either case produces functional effects identical to those of oxidation. Here we have used site-directed spin labeling and double electron-electron resonance (DEER), a pulsed EPR technique that measures distances between spin labels, to characterize the structural changes resulting from these mutations. Spin labels were attached to a pair of introduced cysteine residues, one in the C-lobe (T117C) and one in the N-lobe (T34C) of CaM, and DEER was used to determine the distribution of interspin distances. Ca binding induced a large increase in the mean distance, in concert with previous x-ray crystallography and NMR data, showing a closed structure in the absence of Ca and an open structure in the presence of Ca. DEER revealed additional information about CaM’s structural heterogeneity in solution: In both the presence and absence of Ca, CaM populates both structural states, one with probes separated by ~4 nm (closed) and another at ~6 nm (open). Ca shifts the structural equilibrium constant toward the open state by a factor of 13. DEER reveals the distribution of interprobe distances, showing that each of these states is itself partially disordered, with the width of each population ranging from 1.5 to 3 nm. Both mutations (M109Q and M124Q) decrease the effect of Ca on the structure of CaM, primarily by decreasing the closed-to-open equilibrium constant in the presence of Ca. We propose that Met oxidation alters CaM’s functional interaction with its target proteins by perturbing this Ca-dependent structural shift. PMID:25478640

  14. The Vibration Impact Determination of the Helicopter Structural Components

    Directory of Open Access Journals (Sweden)

    Khaksar Zeinab

    2017-01-01

    Full Text Available This paper presents the determination of the vibration impact of the helicopter structural components and skin repairs in terms of frequency characteristics. To address this issue, a 3D Finite Element Method (FEM model of 349 Gazelle helicopter has been developed in ABAQUS and the frequency analysis is conducted. The results on the natural frequencies of the full structure reasonably match with the literature giving confidence in the baseline model. The main advantage of this FEM model is that, it can be used to predict the natural frequencies of the full structure, precisely. In addition, the material properties and conditions of the components can be updated based on the applied conditions during the repair and maintenance period. Thus, the model gives a comprehensive design tool for analysing the frequencies of the helicopter with differing components. The effective variations in the frequency changes due to repair are predicted numerically. The discussion of these results helps in developing leads to improved selection of replacement materials and their properties.

  15. Impact of chromatin structures on DNA processing for genomic analyses.

    Directory of Open Access Journals (Sweden)

    Leonid Teytelman

    Full Text Available Chromatin has an impact on recombination, repair, replication, and evolution of DNA. Here we report that chromatin structure also affects laboratory DNA manipulation in ways that distort the results of chromatin immunoprecipitation (ChIP experiments. We initially discovered this effect at the Saccharomyces cerevisiae HMR locus, where we found that silenced chromatin was refractory to shearing, relative to euchromatin. Using input samples from ChIP-Seq studies, we detected a similar bias throughout the heterochromatic portions of the yeast genome. We also observed significant chromatin-related effects at telomeres, protein binding sites, and genes, reflected in the variation of input-Seq coverage. Experimental tests of candidate regions showed that chromatin influenced shearing at some loci, and that chromatin could also lead to enriched or depleted DNA levels in prepared samples, independently of shearing effects. Our results suggested that assays relying on immunoprecipitation of chromatin will be biased by intrinsic differences between regions packaged into different chromatin structures - biases which have been largely ignored to date. These results established the pervasiveness of this bias genome-wide, and suggested that this bias can be used to detect differences in chromatin structures across the genome.

  16. The Serra da Cangalha impact structure, Brazil: Geological, stratigraphic and petrographic aspects of a recently confirmed impact structure

    Science.gov (United States)

    Vasconcelos, Marcos Alberto Rodrigues; Crósta, Alvaro P.; Reimold, Wolf Uwe; Góes, Ana Maria; Kenkmann, Thomas; Poelchau, Michael H.

    2013-08-01

    Serra da Cangalha is a complex impact structure with an apparent diameter of 13.7 km located in essentially undisturbed sedimentary rocks of the Parnaíba basin in northeastern Brazil. The stratigraphy of the crater region includes, from bottom to top, the Longá, Poti, Piauí and Pedra de Fogo formations of Devonian to Late Permian age. The age of the impact event is constrained to shatter cones from the central depression. Furthermore, significant cementation with iron oxide is observed in the rocks of Serra da Cangalha, especially in the Poti Formation and in the polymict breccias, conferring to them a peculiar red color. Macroscopic deformation involves faulted, folded and subvertical strata within a ˜2.9 km radius from the center. (ii) The annular basin domain has limited outcrops; its most prominent features are two concentric annular ridges formed by chert breccias and fossilized wood-bearing folded strata of the Pedra de Fogo Formation. (iii) The crater rim and (iv) external domains comprise undisturbed strata of the Pedra de Fogo and Piauí formations with well-preserved sedimentary structures. Whilst the existing literature on Serra da Cangalha has focused on the structure morphology, general geology and some shock features, we present here a detailed description of the stratigraphy and the geology of each formation in the interior and around Serra da Cangalha, as well as further detailed microscopic shock feature analysis. This provides significant evidence that the rocks of the central uplift have undergone shock pressures of, at maximum, 10 GPa.

  17. FLOW STRUCTURE AND SEDIMENT TRANSPORT WITH IMPACTS OF AQUATIC VEGETATION

    Institute of Scientific and Technical Information of China (English)

    LIU Cheng; SHEN Yong-ming

    2008-01-01

    Aquatic vegetation plays an important role in the flow structure of open channels and thus changes the fate and the transport of sediment. This article proposes a three-dimensional turbulence model by introducing vegetation density and drag force into the control equations of water flow in the presence of vegetation. The model was used to calculate the impacts of submerged vegetation on the vertical profiles of longitudinal flow velocities, the changes of the depth-averaged flow velocities in a compound channel with emergent vegetation in the floodplain, the removal of suspended sediment from the channels by emergent vegetation, and the bed changes around and in a vegetated island. Numerical investigations show that aquatic vegetation retards flow in the vegetation zone, reduces the sediment transport capacity, and contributes to erosion on both sides of the vegetated island. Calculated results agree well with experimental results.

  18. Impact of structural characteristics on starch digestibility of cooked rice.

    Science.gov (United States)

    Tamura, Masatsugu; Singh, Jaspreet; Kaur, Lovedeep; Ogawa, Yukiharu

    2016-01-15

    To examine the impact of structural characteristics of cooked rice grains on their starch digestibility, a simulated in vitro gastro-small intestinal digestion technique was applied to intact and homogenised cooked rice samples. The starch hydrolysis percentage increased during simulated small intestinal digestion, in which approximately 65% and 24% of the starch was hydrolysed within the first 5min, for homogenised and intact cooked rice, respectively. The kinetic constant of homogenised cooked rice, which was regarded as an estimated digestion rate, was ∼8 times higher than the intact cooked rice. The homogenised and intact samples were also examined for any microstructural changes occurring during the in vitro digestion process using fluorescent and scanning electron microscopy. In the intact samples, the aleurone layers of the endosperm remained as thin-film like layers during in vitro digestion and thus may be regarded as less digestible materials that influence cooked rice digestibility.

  19. The Ecology of Seamounts: Structure, Function, and Human Impacts

    Science.gov (United States)

    Clark, Malcolm R.; Rowden, Ashley A.; Schlacher, Thomas; Williams, Alan; Consalvey, Mireille; Stocks, Karen I.; Rogers, Alex D.; O'Hara, Timothy D.; White, Martin; Shank, Timothy M.; Hall-Spencer, Jason M.

    2010-01-01

    In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research.

  20. Post-impact hydrothermal system geochemistry and mineralogy: Rochechouart impact structure, France.

    Science.gov (United States)

    Simpson, Sarah

    2014-05-01

    Hypervelocity impacts generate extreme temperatures and pressures in target rocks and may permanently alter them. The process of cratering is at the forefront of research involving the study of the evolution and origin of life, both on Mars and Earth, as conditions may be favourable for hydrothermal systems to form. Of the 170 known impact structures on Earth, over one-third are known to contain fossil hydrothermal systems [1]. The introduction of water to a system, when coupled with even small amounts of heat, has the potential to completely alter the target or host rock geochemistry. Often, the mineral assemblages produced in these environments are unique, and are useful indicators of post-impact conditions. The Rochechouart impact structure in South-Central France is dated to 201 ± 2 Ma into a primarily granitic target [2]. Much of the original morphological features have been eroded and very little of the allochthonous impactites remain. This has, however, allowed researchers to study the shock effects on the lower and central areas of the structure, as well as any subsequent hydrothermal activity. Previous work has focused on detailed classification of the target and autochthonous and allochthonous impactites [3, 4], identification of the projectile [5], and dating the structure using Ar-isotope techniques [2]. Authors have also noted geochemical evidence of K-metasomatism, which is pronounced throughout all lithologies as enrichment in K2O and depletion in CaO and Na2O [3, 4, 5]. This indicates a pervasive hydrothermal system, whose effects throughout the structure have yet to be studied in detail, particularly in those parts at and below the transient floor. The purpose of this study is to classify the mineralogical and geochemical effects of the hydrothermal system. Samples were collected via permission from the Réserve Naturelle de l'Astroblème de Rochechouart-Chassenon [6]. Sample selection was based on the presence of secondary mineralization in hand

  1. Monoclinic tridymite in clast-rich impact melt rock from the Chesapeake Bay impact structure

    Science.gov (United States)

    Jackson, J.C.; Horton, J.W.; Chou, I.-Ming; Belkin, H.E.

    2011-01-01

    X-ray diffraction and Raman spectroscopy confirm a rare terrestrial occurrence of monoclinic tridymite in clast-rich impact melt rock from the Eyreville B drill core in the Chesapeake Bay impact structure. The monoclinic tridymite occurs with quartz paramorphs after tridymite and K-feldspar in a microcrystalline groundmass of devitrified glass and Fe-rich smectite. Electron-microprobe analyses revealed that the tridymite and quartz paramorphs after tridymite contain different amounts of chemical impurities. Inspection by SEM showed that the tridymite crystal surfaces are smooth, whereas the quartz paramorphs contain irregular tabular voids. These voids may represent microporosity formed by volume decrease in the presence of fluid during transformation from tridymite to quartz, or skeletal growth in the original tridymite. Cristobalite locally rims spherulites within the same drill core interval. The occurrences of tridymite and cristobalite appear to be restricted to the thickest clast-rich impact melt body in the core at 1402.02-1407.49 m depth. Their formation and preservation in an alkali-rich, high-silica melt rock suggest initially high temperatures followed by rapid cooling.

  2. Osmium-Isotope and Platinum-Group-Element Systematics of Impact-Melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA

    Science.gov (United States)

    Lee, Seung Ryeol; Wright Horton, J., Jr.; Walker, Richard J.

    2005-01-01

    Osmium (Os) isotopes and platinum-group elements (PGEs) are useful for geochemically identifying a meteoritic component within impact structures, because meteorites are typically characterized by low (187)Os/(188)Os ratios and high PGE concentrations. In contrast, most types of crustal target rocks have high radiogenic Os and very low PGE concentrations. We have examined Os isotope and PGE systematics of impact-melt rocks and pre-impact target rocks from a 2004 test hole in the late Eocene Chesapeake Bay impact structure and from nearby coreholes. Our goal is to determine the proportion of the projectile component in the melt rock Additional information is included in the original extended abstract.

  3. Car Side Structure Crashworthiness in Pole and Moving Deformable Barrier Side Impacts

    Institute of Scientific and Technical Information of China (English)

    WANG Dazhi; DONG Guang; ZHANG Jinhuan; HUANG Shilin

    2006-01-01

    To clearly understand passenger car structure's crashworthiness in typical side impacts of pole and moving deformable barrier (MDB) impact modes, which could assist the establishment of Chinese vehicle side impact safety regulations, a full midsized car finite element model, calibrated by pole side impact test, was built and the pole side impact according to European New Car Assessment Program (EuroNCAP) and the MDB side impact according to ECE R95 regulations were simulated with LS-DYNA. The accelerations and the structure deformations from simulations were compared. It can be concluded that the pole side impact focuses primarily on side structure crashworthiness as a result of large intrusions, while the MDB side impact focuses primarily on full side structure crashworthiness. Accordingly, occupant protection strategies focus on different aspects to improve side impact safety. In the pole side impact the objective is to maintain the passenger compartment and protect the passenger's head from impacting the pole, while in the MDB side impact the objective is to protect the full human body. In the design of the car side structures, at least these two tests should be considered for assessing their side impact crashworthiness. Conducting these two side impact tests as certified tests provides insights into car safety during side impacts.

  4. The Raman Signature of Shocked Carbonates from the Haughton Impact Structure, Devon Island, Canada

    Science.gov (United States)

    Lindgren, P.; Broman, C.; Holm, N. G.; Parnell, J.; Bowden, S. A.; Osinski, G. R.; Lee, P.

    2009-03-01

    This is a study of the Raman signature of calcite and dolomite in shocked carbonate clasts within the Haughton impact melt rocks. The impact shock effects are observed with Raman analyses in dolomite, while the calcite structure remains intact.

  5. Energy profile and secondary structure impact shRNA efficacy

    Directory of Open Access Journals (Sweden)

    Zeng Xiao

    2009-07-01

    Full Text Available Abstract Background RNA interference (RNAi is a cellular mechanism in which a short/small double stranded RNA induces the degradation of its sequence specific target mRNA, leading to specific gene silencing. Since its discovery, RNAi has become a powerful biological technique for gene function studies and drug discovery. The very first requirement of applying RNAi is to design functional small interfering RNA (siRNA that can uniquely induce the degradation of the targeted mRNA. It has been shown that many functional synthetic siRNAs share some common characteristics, such as GC content limitation and free energy preferences at both terminals, etc. Results Our three-phase algorithm was developed to design siRNA on a whole-genome scale based on those identified characteristics of functional siRNA. When this algorithm was applied to design short hairpin RNA (shRNA, the validated success rate of shRNAs was over 70%, which was almost double the rate reported for TRC library. This indicates that the designs of siRNA and shRNA may share the same concerns. Further analysis of the shRNA dataset of 444 designs reveals that the high free energy states of the two terminals have the largest positive impact on the shRNA efficacy. Enforcing these energy characteristics of both terminals can further improve the shRNA design success rate to 83.1%. We also found that functional shRNAs have less probability for their 3' terminals to be involved in mRNA secondary structure formation. Conclusion Functional shRNAs prefer high free energy states at both terminals. High free energy states of the two terminals were found to be the largest positive impact factor on shRNA efficacy. In addition, the accessibility of the 3' terminal is another key factor to shRNA efficacy.

  6. Comparison of Response between RC and SC Containment Structures Subjected to Aircraft Impact

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sang Shup; Choi, In Kil [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Tae Hyo [Hanyang University, Seoul (Korea, Republic of)

    2012-05-15

    Since the aircraft terror to the World Trade Center (WTC) on September 11, 2001, an aircraft impact problem has been increasingly interested. The possibilities of aircraft impacts against nuclear power plants are one of important category. To date, the impact load of the analysis on aircraft impacts has been applied to target structures in local areas by using the impact force-time history function of Riera. However, Riera forcing function is not recommended at the expectation of unreasonable damage or perforation to target structures. The numerical analysis of rc and sc containment structures subjected to aircraft impact is performed by using the AUTODYN-3D. It is carried out the four different types for RC and SC structures. Thus, in this study, the different behaviors of containment structures and the safety of SC structure are expected

  7. Experimental Study and Numerical Simulation of Hypervelocity Projectile Impact on Double-Wall Structure

    Institute of Scientific and Technical Information of China (English)

    陈沿海; 张庆明; 黄风雷

    2004-01-01

    Tests of hypervelocity projectile impact on double-wall structure were performed with the front wall ranging from 0.5 mm to 2.0 mm thick and different impact velocities. Smooth particle hydrodynamics (SPH) code in LS-DYNA was employed for the simulation of hypervelocity impact on the double-wall structure. By using elementary shock wave theory, the experimental results above are analyzed. The analysis can provide an explanation for the penetration mechanism of hypervelocity projectile impact on double-wall structure about the effect of front wall thickness and impact velocity.

  8. Impact of Demographic Structure on Paddy and Forestland Management

    Institute of Scientific and Technical Information of China (English)

    LI Tiehua; XIANG Wenhua; XU Guozhen; ZENG Guangzheng

    2006-01-01

    In order to understand the impact of demographic structure on paddy and forestland management after the convening of the Third Plenary Session of the 11"1 CPC (Communist Party of China) Central Committee and the implementation of the Household Responsibility System (the government divided up land among peasants for cultivating and the peasants sell a set part of their produced goods to the government at stipulated prices by contract in the countryside of China), 147 households in 6 villages, belonging to Xiangtan County and Zhuzhou County in Hunan Province, were selected as research samples, and interview, questionnaire survey and second hand data analyzing were used as the methods. The results showed: Persons with different ages had different ideas, and young peasants would like to work in towns or cities for more income, so they used and depended on land less; In terms of sex, the male was still the main user of land, and therefore the ability, idea and activity of male played an important role in land management; Generally, the labors with better educational background grasped more knowledge and technologies, and they had more opportunity to get jobs and had better working condition and more income in town or cities, so they depended on and used land less.

  9. Impact of Corrugated Paperboard Structure on Puncture Resistance

    Directory of Open Access Journals (Sweden)

    Vaidas Bivainis

    2015-03-01

    Full Text Available Thanks to its excellentprotective properties, lightness, a reasonable price, and ecology, corrugated paperboardis one of the most popular materials used in the production of packaging for variousproducts. During transportation or storage, packaging with goods can be exposedto the mass of other commodities, dropping from heights and transportationshock loads, which can lead to their puncture damage. Depending on the purposeand size of the packaging, the thickness, grammage, constituent paper layers,numbers of layers and type of fluting of corrugated paperboard used in itsproduction differ. A standard triangular prism, corrugated paperboard fixationplates and a universal tension-compression machine were used to investigate theimpact of corrugated paperboard structure and other parameters on the punctureresistance of the material. The investigation determines the maximum punctureload and estimates energy required to penetrate the corrugated paperboard. Itwas found that the greatest puncture resistance is demonstrated by paperboardwith a larger number of corrugating flutings and the board produced from harderpaper with a smaller amount of recycled paper. It was established that thegrammage of three-layered paperboard with two different fluting profiles has thegreatest impact on the level of static puncture energy.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5713

  10. Prompt Gas Desorption Due to Ion Impact on Accelerator Structures

    Science.gov (United States)

    Vijay, Sagar; Seidl, Peter A.; Faltens, Andy; Lidia, Steven M.

    2011-10-01

    The repetition rate and peak current of high intensity ion accelerators for inertial fusion or other applications may be limited under certain conditions by the desorption of gas molecules and atoms due to stray ions striking the accelerator structure. We have measured the prompt yield of atoms in close proximity to the point of impact of the ions on a surface. Using the 300-keV, K+ ion beam of the Neutralized Drift Compression Experiment (NDCX-I), ions strike a metal target in a 5-10 microsecond bunch. The collector of a Bayert-Alpert style ionization gauge is used to detect the local pressure burst several centimeters away. Pressure transients are observed on a micro-second time scale due to the initial burst of desorbed gas, and on a much longer (~1 second) timescale, corresponding to the equilibration of the pressure after many ``bounces'' of atoms in the vacuum chamber. We report on these time dependent pressure measurements, modeling of the pressure transient, and implications for high-intensity ion accelerators. Work performed under auspices of U.S. DOE by LBNL under Contract DE-AC02-05CH1123.

  11. Societal Implications of an Impact Crater - Chesapeake Bay Impact Structure, Virginia

    Science.gov (United States)

    Emry, S.; McFarland, R.; Powars, D.

    2002-05-01

    to support a five-year cooperative effort to determine the effects of the impact structure on the ground water resources for the Coastal Plain System and to revise an aging Coastal Plain ground water flow model to be used in managing the resource. Other partners include the Department of Geological Sciences at the College of William and Mary and the National Aeronautics and Space Administration's Langley Research Center. The project has grown to include the involvement of several divisions within the U.S. Geological Survey and the interest of researchers from across this world.

  12. Comparison of petrophysical properties of impactites for four meteoritic impact structures

    Science.gov (United States)

    Popov, Y.; Mayr, S.; Romushkevich, R.; Burkhardt, H.; Wilhelm, H.

    2014-05-01

    We reanalyzed and compared unique data sets, which we obtained in the frame of combined petrophysical and geothermal investigations within scientific drilling projects on four impact structures: the Puchezh-Katunki impact structure (Vorotilovo borehole, Russia), the Ries impact structure (Noerdlingen-73 borehole, Germany), the Chicxulub impact structure (ICDP Yaxcopoil-1 borehole, Mexico), and the Chesapeake impact structure (ICDP-USGS-Eyreville borehole, USA). For a joined interpretation, we used the following previously published data: thermal properties, using the optical scanning technique, and porosities, both measured on densely sampled halfcores of the boreholes. For the two ICDP boreholes, we also used our previously published P-wave velocities measured on a subset of cores. We show that thermal conductivity, thermal anisotropy, porosity, and velocity can be correlated with shock metamorphism (target rocks of the Puchezh-Katunki and Ries impact structures), and confirm the absence of shock metamorphism in the samples taken from megablocks (Chicxulub and Chesapeake impact structure). The physical properties of the lithic impact breccias and suevites are influenced mainly by their impact-related porosity. Physical properties of lower porosity lithic impact breccias and suevites are also influenced by their chemical composition. These data allow for a distinction between different types of breccias due to differences concerning the texture and chemistry and the different amounts of melt and rock clasts.

  13. Characterization of Carbonaceous Material from the Sudbury Impact Structure Using Raman Microspectroscopy

    Science.gov (United States)

    Wright, A. J.; Parnell, J.; Ames, D. E.

    2008-03-01

    Samples from the 1.85 Ga Sudbury impact structure have been analyzed using Raman microspectroscopy in order to characterize the carbonaceous material and to investigate the relationship between the carbonaceous strata associated with the structure.

  14. Spatial impacts of urban structures on micrometeorological variables

    Science.gov (United States)

    Koelbing, Merle; Schuetz, Tobias; Weiler, Markus

    2016-04-01

    The heterogeneity of urban surfaces including buildings and the urban vegetation causes high variability of micrometeorological variables on small spatial scales which makes it hard to observe or even predict climate conditions and in particular evapotranspiration with high resolution on the scale of entire cities. Regarding future climate changes and their impacts on urban climate and hydrology the predictability of these small scale variations becomes more and more relevant i.e. for city planners to improve the development of appropriate mitigation strategies. Therefore, new transfer functions for meteorological variables are needed, which consider the structural variability in urban areas and its impacts on the energy balance (shading effects, ventilation, lateral longwave energy fluxes). We approach this goal by testing a mobile meteorological station (the station is mounted on a bicycle trailer and transported by an E-Bike) as a means to derive empirical spatial transfer functions for specific urban structures. We observe air temperature and relative air humidity at 2 different heights, wind direction and speed, incoming and outgoing shortwave radiation as well as infrared temperature from above and below and the four directions. First measurements have been performed in December 2015 at 22 locations in four clusters, which represent manifold different characteristics of urban areas within the city of Freiburg. Every location has been monitored two to six times. Overall, nearly 200 measurements of each variable have been taken. Each measurement takes five minutes. Values are logged every 15 seconds. These measurements were analyzed with regard to a climate station mounted on a rooftop in the proximity of all clusters. Results show a systematic pattern in the differences between the values taken with the fixed and those taken with the mobile climate station, depending on the measurement locations. For example, lower air temperature and higher relative air

  15. Impact of oil on bacterial community structure in bioturbated sediments.

    Directory of Open Access Journals (Sweden)

    Magalie Stauffert

    Full Text Available Oil spills threaten coastlines where biological processes supply essential ecosystem services. Therefore, it is crucial to understand how oil influences the microbial communities in sediments that play key roles in ecosystem functioning. Ecosystems such as sediments are characterized by intensive bioturbation due to burrowing macrofauna that may modify the microbial metabolisms. It is thus essential to consider the bioturbation when determining the impact of oil on microbial communities. In this study, an experimental laboratory device maintaining pristine collected mudflat sediments in microcosms closer to true environmental conditions--with tidal cycles and natural seawater--was used to simulate an oil spill under bioturbation conditions. Different conditions were applied to the microcosms including an addition of: standardized oil (Blend Arabian Light crude oil, 25.6 mg.g⁻¹ wet sediment, the common burrowing organism Hediste (Nereis diversicolor and both the oil and H. diversicolor. The addition of H. diversicolor and its associated bioturbation did not affect the removal of petroleum hydrocarbons. After 270 days, 60% of hydrocarbons had been removed in all microcosms irrespective of the H. diversicolor addition. However, 16S-rRNA gene and 16S-cDNA T-RFLP and RT-PCR-amplicon libraries analysis showed an effect of the condition on the bacterial community structure, composition, and dynamics, supported by PerMANOVA analysis. The 16S-cDNA libraries from microcosms where H. diversicolor was added (oiled and un-oiled showed a marked dominance of sequences related to Gammaproteobacteria. However, in the oiled-library sequences associated to Deltaproteobacteria and Bacteroidetes were also highly represented. The 16S-cDNA libraries from oiled-microcosms (with and without H. diversicolor addition revealed two distinct microbial communities characterized by different phylotypes associated to known hydrocarbonoclastic bacteria and dominated by

  16. Probability of Detection Study on Impact Damage to Honeycomb Composite Structure using Thermographic Inspection

    Science.gov (United States)

    Hodge, Andrew J.; Walker, James L., II

    2008-01-01

    A probability of detection study was performed for the detection of impact damage using flash heating infrared thermography on a full scale honeycomb composite structure. The honeycomb structure was an intertank structure from a previous NASA technology demonstration program. The intertank was fabricated from IM7/8552 carbon fiber/epoxy facesheets and aluminum honeycomb core. The intertank was impacted in multiple locations with a range of impact energies utilizing a spherical indenter. In a single blind study, the intertank was inspected with thermography before and after impact damage was incurred. Following thermographic inspection several impact sites were sectioned from the intertank and cross-sectioned for microscopic comparisons of NDE detection and actual damage incurred. The study concluded that thermographic inspection was a good method of detecting delamination damage incurred by impact. The 90/95 confidence level on the probability of detection was close to the impact energy that delaminations were first observed through cross-sectional analysis.

  17. 16 CFR Figure 1 to Subpart A of... - Glass Impact Test Structure

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Glass Impact Test Structure 1 Figure 1 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT... 1 to Subpart A of Part 1201—Glass Impact Test Structure EC03OC91.004...

  18. The Structure of Arizaro, Salta, Argentina: A New Simple Type Meteorite Impact Site?

    Science.gov (United States)

    Acevedo, R. D.; Rocca, M.; Alonso, R.; Rabassa, J.; Ponce, J. F.; Klajnik, K.

    2012-09-01

    A possible new impact crater had been found in Puna, Argentina: the structure of Arizaro (24º 55" 45.30” S, 67º 27" 09.64” W), located at 3,650 m.a.s.l. This structure is probably a new young simple-type impact crater on Tertiary-Quaternary sedimentary deposits.

  19. Market power versus capital structure determinants: Do they impact leverage?

    Directory of Open Access Journals (Sweden)

    Agha Jahanzeb

    2015-12-01

    Full Text Available The purpose of this study is to investigate the association between market power and capital structure. This study will further provide a logical explanation towards the factors affecting capital structure. This study analysed 176 non-financial Pakistani companies listed on Karachi Stock Exchange over the period of 2003–2012. Capital structure has been tried to investigate with a different perspective by investigating its association with market power. It has been seen that there is a significant and positive relation between market power and capital structure. Size and liquidity remained significantly negative with capital structure, whereas profitability and dividend payout remained significantly positive with capital structure. To the best of authors’ knowledge, this is the first study that investigates the relationship between market power and capital structure in any developing economy by employing the data of non-financial Pakistani firms.

  20. Real-Time Impact Visualization Inspection of Aerospace Composite Structures with Distributed Sensors.

    Science.gov (United States)

    Si, Liang; Baier, Horst

    2015-07-08

    For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor and predict the locations and force magnitudes of unforeseen foreign impacts on composite structures and to estimate in real time mode the structural state when impacts occur. The proposed smart impact visualization inspection (IVI) technique mainly consists of five functional modules, which are the signal data preprocessing (SDP), the forward model generator (FMG), the impact positioning calculator (IPC), the inverse model operator (IMO) and structural state estimator (SSE). With regard to the verification of the practicality of the proposed IVI technique, various structure configurations are considered, which are a normal CFRP panel and another CFRP panel with "orange peel" surfaces and a cutout hole. Additionally, since robustness against several background disturbances is also an essential criterion for practical engineering demands, investigations and experimental tests are carried out under random vibration interfering noise (RVIN) conditions. The accuracy of the predictions for unknown impact events on composite structures using the IVI technique is validated under various structure configurations and under changing environmental conditions. The evaluated errors all fall well within a satisfactory limit range. Furthermore, it is concluded that the IVI technique is applicable for impact monitoring, diagnosis and assessment of aerospace composite structures in complex practical engineering environments.

  1. The Chicxulub impact structure: What does the Yaxcopoil-1 drill core reveal?

    Science.gov (United States)

    Elbra, T.

    2013-05-01

    The Chicxulub impact structure, one of the largest impact structures on Earth, was formed 65 Ma by hypervelocity impact which led to the large mass-extinction at K-Pg boundary. This well preserved but buried structure has undergone numerous drillings and studies aimed to understand the formation mechanism, structure and age of the crater. The Yaxcopoil-1 (Yax-1) drill core, located in the southern sector of the Chicxulub crater, in the outer part of an annular trough, 62 km from the crater center, was drilled by ICDP in 2001-2002. Petrophysical, rock- and paleomagnetic studies of Yax-1 (Elbra and Pesonen, 2011) showed that physical properties characterize the various lithological units. Dependence on mineral composition rather than fabric was observed in pre-impact lithologies contrarily to the post-impact and impact rocks where the physical properties were dominated by porosity and reflected, in case of impactites, the impact formation mechanism with its numerous features resulting from melting, brecciation and fracturing. Furthermore, while the pre- and post-impact lithologies in Yax-1 are mostly dia- or paramagnetic, the impactite units indicated enhanced magnetizations and the presence of ferromagnetic, probably hydrothermally deposited magnetite and pyrrhotite. The sharp contrast of the impactites to the target and to post-impact lithologies allowed establishing the contact (especially the K-Pg boundary) between. The anisotropy, shape and orientation of the magnetic fraction illustrated the fabric randomization and showed the influence of impact-related redeposition and hydrothermal activity. The paleomagnetic data suggested that the Chicxulub impact occurred during the reverse polarity geomagnetic chron 29R, which is in agreement with the isotopic dates of the Chicxulub impact as well as with expected K-Pg boundary polarity. Reference Elbra, T. and Pesonen, L.J., 2011. Physical properties of the Yaxcopoil-1 deep drill core, Chicxulub impact structure, Mexico

  2. Three-dimensional water impact at normal incidence to a blunt structure

    Science.gov (United States)

    Chatjigeorgiou, I. K.; Cooker, M. J.; Korobkin, A. A.

    2016-08-01

    The three-dimensional water impact onto a blunt structure with a spreading rectangular contact region is studied. The structure is mounted on a flat rigid plane with the impermeable curved surface of the structure perpendicular to the plane. Before impact, the water region is a rectangular domain of finite thickness bounded from below by the rigid plane and above by the flat free surface. The front free surface of the water region is vertical, representing the front of an advancing steep wave. The water region is initially advancing towards the structure at a constant uniform speed. We are concerned with the slamming loads acting on the surface of the structure during the initial stage of water impact. Air, gravity and surface tension are neglected. The problem is analysed by using some ideas of pressure-impulse theory, but including the time-dependence of the wetted area of the structure. The flow caused by the impact is three-dimensional and incompressible. The distribution of the pressure-impulse (the time-integral of pressure) over the surface of the structure is analysed and compared with the distributions provided by strip theories. The total impulse exerted on the structure during the impact stage is evaluated and compared with numerical and experimental predictions. An example calculation is presented of water impact onto a vertical rigid cylinder. Three-dimensional effects on the slamming loads are the main concern in this study.

  3. Towards reliable simulations of ballistic impact on concrete structures

    NARCIS (Netherlands)

    Khoe, Y.S.; Tyler Street, M.D.; Maravalalu Suresh,, R.S.; Weerheijm, J.

    2013-01-01

    Protection against weapon effects like ballistic impacts, fragmenting shells and explosions is the core business of the Explosions, Ballistics and Protection department of TNO (The Netherlands). Experimental and numerical research is performed to gain and maintain the knowledge to support the Dutch

  4. Droplet impact on superheated micro-structured surfaces

    NARCIS (Netherlands)

    Tran, A.T.; Staat, H.J.J.; Susarrey-Arce, A.; Foertsch, T.C.; Houselt, van A.; Gardeniers, J.G.E.; Prosperetti, A.; Lohse, D.; Sun, C.

    2013-01-01

    When a droplet impacts upon a surface heated above the liquid's boiling point, the droplet either comes into contact with the surface and boils immediately (contact boiling), or is supported by a developing vapor layer and bounces back (film boiling, or Leidenfrost state). We study the transition be

  5. Modelling hypervelocity impacts into aluminum structures based on LDEF data

    Science.gov (United States)

    Coombs, C. R.; Atkinson, D. R.; Watts, A. J.; Wagner, J. R.; Allbrooks, M. K.; Hennessy, C. J.

    1993-01-01

    Realizing and understanding the effects of the near-Earth space environment on a spacecraft during its mission lifetime is becoming more important with the regeneration of America's space program. Included among these potential effects are the following: erosion and surface degradation due to atomic oxygen impingement; ultraviolet exposure embrittlement; and delamination, pitting, cratering, and ring formation due to micrometeoroid and debris impacts. These effects may occur synergistically and may alter the spacecraft materials enough to modify the resultant crater, star crack, and/or perforation. This study concentrates on modelling the effects of micrometeoroid and debris hypervelocity impacts into aluminum materials (6061-T6). Space debris exists in all sizes, and has the possibility of growing into a potentially catastrophic problem, particularly since self-collisions between particles can rapidly escalate the number of small impactors. We have examined the morphologies of the Long Duration Exposure Facility (LDEF) impact craters and the relationship between the observed impact damage on LDEF versus the existing models for both the natural (micrometeoroid) and manmade (debris) environments in order to better define these environments.

  6. Towards reliable simulations of ballistic impact on concrete structures

    NARCIS (Netherlands)

    Khoe, Y.S.; Tyler Street, M.D.; Maravalalu Suresh,, R.S.; Weerheijm, J.

    2013-01-01

    Protection against weapon effects like ballistic impacts, fragmenting shells and explosions is the core business of the Explosions, Ballistics and Protection department of TNO (The Netherlands). Experimental and numerical research is performed to gain and maintain the knowledge to support the Dutch

  7. Impact factors of fractal analysis of porous structure

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Characterization of pore structure is one of the key problems for fabrication and application research on porous materials. But, complexity of pore structure makes it difficult to characterize pore structure by Euclidean geometry and traditional experimental methods. Fractal theory has been proved effective to characterize the complex pore structure. The box dimension method based on fractal theory was applied to characterizing the pore structure of fiber porous materials by analyzing the electronic scanning microscope (SEM) images of the porous materials in this paper. The influences of image resolution, threshold value, and image magnification on fractal analysis were investigated. The results indicate that such factors greatly affect fractal analysis process and results. The appropriate magnification threshold and fractal analysis are necessary for fractal analysis.

  8. Fluid Structure Interaction Effects on Composites Under Low Velocity Impact

    Science.gov (United States)

    2012-06-01

    Interaction, FSI, low velocity impact, carbon fiber reinforced polymers, CFRP, carbon nanotubes, CNT, vacuum assisted resin transfer molding, VARTM . 16...Ethyl Ketone Peroxide MWCNT Multi-Walled Carbon Nanotube VARTM Vacuum-Assisted Resin Transfer Molding xiv THIS PAGE INTENTIONALLY LEFT BLANK...samples used in this research is known as vacuum assisted resin transfer molding ( VARTM ). VARTM is a very common method used in low pressure composite

  9. Impact of aging and material structure on CANDU plant performance

    Energy Technology Data Exchange (ETDEWEB)

    Nadeau, E.; Ballyk, J.; Ghalavand, N. [Candu Energy Inc., Mississauga, Ontario (Canada)

    2011-07-01

    In-service behaviour of pressure tubes is a key factor in the assessment of safety margins during plant operation. Pressure tube deformation (diametral expansion) affects fuel bundle dry out characteristics resulting in reduced margin to trip for some events. Pressure tube aging mechanisms also erode design margins on fuel channels or interfacing reactor components. The degradation mechanisms of interest are primarily deformation, loss of fracture resistance and hydrogen ingress. CANDU (CANada Deuterium Uranium, a registered trademark of the Atomic Energy of Canada Limited used under exclusive licence by Candu Energy Inc.) owners and operators need to maximize plant capacity factor and meet or exceed the reactor design life targets while maintaining safety margins. The degradation of pressure tube material and geometry are characterized through a program of inspection, material surveillance and assessment and need to be managed to optimize plant performance. Candu is improving pressure tubes installed in new build and life extension projects. Improvements include changes designed to reduce or mitigate the impact of pressure tube elongation and diametral expansion rates, improvement of pressure tube fracture properties, and reduction of the implications of hydrogen ingress. In addition, Candu provides an extensive array of engineering services designed to assess the condition of pressure tubes and address the impact of pressure tube degradation on safety margins and plant performance. These services include periodic and in-service inspection and material surveillance of pressure tubes and deterministic and probabilistic assessment of pressure tube fitness for service to applicable standards. Activities designed to mitigate the impact of pressure tube deformation on safety margins include steam generator cleaning, which improves trip margins, and trip design assessment to optimize reactor trip set points restoring safety and operating margins. This paper provides an

  10. Effect of grain structure on Charpy impact behavior of copper

    Science.gov (United States)

    Liang, Ningning; Zhao, Yonghao; Wang, Jingtao; Zhu, Yuntian

    2017-03-01

    Nanostructured (NS) and ultrafine-grained (UFG) materials have high strength and relatively low ductility. Their toughness has not been comprehensively investigated. Here we report the Charpy impact behavior and the corresponding microstructural evolutions in UFG Cu with equi-axed and elongated grains which were prepared by equal channel angular pressing (ECAP) for 2 and 16 passes at room temperature. It is found that their impact toughness (48 J/cm2) is almost comparable to that of coarse grained (CG) Cu: 55 J/cm2. The high strain rate during the Charpy impact was found to enhance the strain hardening capability of the UFG Cu due to the suppression of dynamic dislocation recovery. The crack in the CG Cu was blunted by dislocation-slip mediated plastic deformation, while the cracks in the UFG Cu were formed at grain boundaries and triple junctions due to their limited plasticity. Near the crack surfaces the elongated grains in ECAP-2 sample were refined by recrystallization, while equi-axed grains in the ECAP-16 sample grew larger.

  11. Effect of grain structure on Charpy impact behavior of copper

    Science.gov (United States)

    Liang, Ningning; Zhao, Yonghao; Wang, Jingtao; Zhu, Yuntian

    2017-01-01

    Nanostructured (NS) and ultrafine-grained (UFG) materials have high strength and relatively low ductility. Their toughness has not been comprehensively investigated. Here we report the Charpy impact behavior and the corresponding microstructural evolutions in UFG Cu with equi-axed and elongated grains which were prepared by equal channel angular pressing (ECAP) for 2 and 16 passes at room temperature. It is found that their impact toughness (48 J/cm2) is almost comparable to that of coarse grained (CG) Cu: 55 J/cm2. The high strain rate during the Charpy impact was found to enhance the strain hardening capability of the UFG Cu due to the suppression of dynamic dislocation recovery. The crack in the CG Cu was blunted by dislocation-slip mediated plastic deformation, while the cracks in the UFG Cu were formed at grain boundaries and triple junctions due to their limited plasticity. Near the crack surfaces the elongated grains in ECAP-2 sample were refined by recrystallization, while equi-axed grains in the ECAP-16 sample grew larger. PMID:28303950

  12. X-Ray Diffraction Powder Patterns and Thin Section Observations from the Sierra Madera Impact Structure

    Science.gov (United States)

    Huson, S. A.; Foit, F. F.; Watkinson, A. J.; Pope, M. C.

    2006-03-01

    X-Ray powder diffraction analysis and thin section observations of carbonate and siliciclastic samples from the Sierra Madera impact structure indicate moderate shock pressures (8 to 30 GPa) were generated during the formation of this crater.

  13. Impact of stock market structure on intertrade time and price dynamics

    National Research Council Canada - National Science Library

    Ivanov, Plamen Ch; Yuen, Ainslie; Perakakis, Pandelis

    2014-01-01

    ... of the corresponding price fluctuations. We report that market structure strongly impacts the scale-invariant temporal organisation in the transaction timing of stocks, which we have observed to have long-range power-law correlations...

  14. Shatter Cones in Basalt: A Natural Example from the Vista Alegre Impact Structure, Brazil

    Science.gov (United States)

    Pittarello, L.; Nestola, F.; Viti, C.; Crósta, A. P.; Koeberl, C.

    2015-09-01

    Shatter cones, formed in fine-grained basalt in the Vista Alegre impact structure (Brazil), exhibit cataclastic layers sub-parallel to the striated surfaces and a continuous melt rock film, investigated with TEM, decorating the striated surface.

  15. Cleanskin Structure, Northern Territory and Queensland, Australia: Evidence for an Impact Origin

    Science.gov (United States)

    Haines, P. W.; Sweet, I. P.; Mitchell, K.

    2012-09-01

    The Cleanskin structure, Australia, is a 15 km diameter circular feature with central uplift. Evidence for impact-produced shock includes shatter cones, planar fractures with feather features and possible planar deformation features in quartz.

  16. Vulnerability Assessment for a Complex Structure Using Vibration Response Induced by Impact Load

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeongwon; Park, Junhong [Hanyang University, Seoul (Korea, Republic of); Koo, Man Hoi [Agency for Defense Development, Daejeon (Korea, Republic of)

    2014-10-15

    This work presents a vulnerability assessment procedure for a complex structure using vibration characteristics. The structural behavior of a three-dimensional framed structure subjected to impact forces was predicted using the spectral element method. The Timoshenko beam function was applied to simulate the impact wave propagations induced by a high-velocity projectile at relatively high frequencies. The interactions at the joints were analyzed for both flexural and longitudinal wave propagations. Simulations of the impact energy transfer through the entire structure were performed using the transient displacement and acceleration responses obtained from the frequency analysis. The kill probabilities of the crucial components for an operating system were calculated as a function of the predicted acceleration amplitudes according to the acceptable vibration levels. Following the proposed vulnerability assessment procedure, the vulnerable positions of a three-dimensional combat vehicle with high possibilities of damage generation of components by impact loading were identified from the estimated vibration responses.

  17. Regional impacts of technical change: the case of structural particleboard in the United States.

    Science.gov (United States)

    Zhi Xu; David N. Bengston; Hans M. Gregersen; Allen L. Lundgren

    1992-01-01

    Analyzes the regional impacts of research benefits in the United States due to the introduction of structural particleboard. The distribution of consumer benefits, producer benefits, direct employment impacts, and changes in wood requirements are analyzed for the four census regions. The distribution of benefits is found to differ widely between regions, indicating...

  18. Understanding the Impact of Trauma Exposure on Posttraumatic Stress Symptomatology: A Structural Equation Modeling Approach

    Science.gov (United States)

    Chen, Wei; Wang, Long; Zhang, Xing-Li; Shi, Jian-Nong

    2012-01-01

    The objective of this study was to investigate the impact of trauma exposure on the posttraumatic stress symptomatology (PTSS) of children who resided near the epicenter of the 2008 Wenchuan earthquake. The mechanisms of this impact were explored via structural equation models with self-esteem and coping strategies included as mediators. The…

  19. Understanding the Impact of Trauma Exposure on Posttraumatic Stress Symptomatology: A Structural Equation Modeling Approach

    Science.gov (United States)

    Chen, Wei; Wang, Long; Zhang, Xing-Li; Shi, Jian-Nong

    2012-01-01

    The objective of this study was to investigate the impact of trauma exposure on the posttraumatic stress symptomatology (PTSS) of children who resided near the epicenter of the 2008 Wenchuan earthquake. The mechanisms of this impact were explored via structural equation models with self-esteem and coping strategies included as mediators. The…

  20. Simulation of the Crashing of Sandwich Structures under Impact Loads by Movable Cellular Automata

    Institute of Scientific and Technical Information of China (English)

    HUANG De-wu; HUANG Hai; SONG Yi; A I Dmitriev; E V Shilko; S G Psakhie

    2005-01-01

    Movable cellular automata (MCA) method is applied in the analysis of dynamic characters of ceramic armor composite structures under impact loading. As a new approach, MCA is different from the traditional numerical methods such as the finite element method and boundary element method. Based on the theory of particle mechanics, MCA is applied as a powerful tool in solving specific structural analysis of materials loss and penetrating damages. In this paper the method is used to study responses of multi-layered ceramic plates as a base of armor structures under impact loading, thus assisting further investigations in the crashing process and to improve ceramic armor structures.

  1. Optimization of large amorphous silicon and silica structures for molecular dynamics simulations of energetic impacts

    Energy Technology Data Exchange (ETDEWEB)

    Samela, Juha, E-mail: juha.samela@helsinki.fi [Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 43, FI-00014 University of Helsinki (Finland); Norris, Scott A. [Southern Methodist University, Dallas, TX 75205 (United States); Nordlund, Kai [Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 43, FI-00014 University of Helsinki (Finland); Aziz, Michael J. [School of Engineering and Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138 (United States)

    2011-07-15

    A practical method to create optimized amorphous silicon and silica structures for molecular dynamics simulations is developed and tested. The method is based on the Wooten, Winer, and Weaire algorithm and combination of small optimized blocks to larger structures. The method makes possible to perform simulations of either very large cluster hypervelocity impacts on amorphous targets or small displacements induced by low energy ion impacts in silicon.

  2. Coffee melanoidins: structures, mechanisms of formation and potential health impacts.

    Science.gov (United States)

    Moreira, Ana S P; Nunes, Fernando M; Domingues, M Rosário; Coimbra, Manuel A

    2012-09-01

    During the roasting process, coffee bean components undergo structural changes leading to the formation of melanoidins, which are defined as high molecular weight nitrogenous and brown-colored compounds. As coffee brew is one of the main sources of melanoidins in the human diet, their health implications are of great interest. In fact, several biological activities, such as antioxidant, antimicrobial, anticariogenic, anti-inflammatory, antihypertensive, and antiglycative activities, have been attributed to coffee melanoidins. To understand the potential of coffee melanoidin health benefits, it is essential to know their chemical structures. The studies undertaken to date dealing with the structural characterization of coffee melanoidins have shown that polysaccharides, proteins, and chlorogenic acids are involved in coffee melanoidin formation. However, exact structures of coffee melanoidins and mechanisms involved in their formation are far to be elucidated. This paper systematizes the available information and provides a critical overview of the knowledge obtained so far about the structure of coffee melanoidins, mechanisms of their formation, and their potential health implications.

  3. The Impact of Changes of the Internal Agricultural Structure in Sichuan Province on Farmers’ Income

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    After introducing the status quo of farmers’ net income and gross output value of agriculture of Sichuan Province,and the changes of agricultural output structure,the regression analysis was conducted on the impact of the changes in agricultural structure on the farmers’ net income per capita on the strengthen of the data from Sichuan statistical yearbook and by the way of econometrics.The multiple linear regression analysis was conducted on the impact the changes in crop farming on farmers’ net income by using logarithmic demand model.The results show that the agricultural structure has transformed from the dominant crop farming to the all-around developmental trend covering the dominant industry,animal husbandry and forestry,fishery and the other industries;the animal husbandry has greatest impact on famers’ income per capita and the impact of crop farming is slightly weaker than animal husbandry;the crop farming and animal husbandry develop fairly rapid simultaneously and the two all have great impact in farmers’ income;among animal husbandry,the meat and eggs have relatively great impact on farmers’ income,while in crop farming,grain plays the dominant role in affecting farmers’ income,followed by cash crop.Hence,the relevant countermeasures applied to increase farmers’ income are put forward in terms of optimizing the internal structure of agriculture,adjusting the internal structure of crop farming,adjusting the internal structure of animal husbandry and strengthening the support of farmers.

  4. Thermal and Hydrothermal Alteration of Conodonts from Target Bedrock and Impact Breccias From the Haughton Impact Structure, Devon Island, Nunavut, Canada

    Science.gov (United States)

    Mason, C. E.; Repetski, J. E.; Smith, W. C.; Lindgren, P.; Parnell, J.; Lee, P.

    2008-03-01

    Samples of carbonate bedrock and clasts from melt breccia within and near the Haughton impact structure (Tertiary), Devon Island, Canada, yield conodonts that provide new data on the age and thermal history of the impacted rocks.

  5. Modeling of fracture of protective concrete structures under impact loads

    Energy Technology Data Exchange (ETDEWEB)

    Radchenko, P. A., E-mail: radchenko@live.ru; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S. [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation)

    2015-10-27

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  6. Food-web structure of seagrass communities across different spatial scales and human impacts.

    Science.gov (United States)

    Coll, Marta; Schmidt, Allison; Romanuk, Tamara; Lotze, Heike K

    2011-01-01

    Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i) quantify differences in food-web structure across local and regional scales and human impacts, (ii) assess the robustness of seagrass webs to simulated species loss, and (iii) compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of food-web analysis

  7. National customer satisfaction indices: The impact of market structure

    DEFF Research Database (Denmark)

    Eskildsen, Jacob Kjær; Kristensen, Kai

    The popularity of customer satisfaction measurements has grown considerably over the last few years but we know very little about how the structure of the individual markets with respect to the transparency of products and services as well as consumer preferences affects customer satisfaction. Here...... a total of 14540 customers have evaluated their preferred supplier with respect to banking, property insurance, supermarkets and mobile telecom. The analysis shows that market structure has a profound effect on customer satisfaction measurements and that this effect differs from industry to industry....... The paper concludes with an evaluation of the implications of the findings in relation to the use of results from customer satisfaction studies....

  8. National customer satisfaction indices: The impact of market structure

    DEFF Research Database (Denmark)

    Eskildsen, Jacob Kjær; Kristensen, Kai

    The popularity of customer satisfaction measurements has grown considerably over the last few years but we know very little about how the structure of the individual markets with respect to the transparency of products and services as well as consumer preferences affects customer satisfaction. Here...... a total of 14540 customers have evaluated their preferred supplier with respect to banking, property insurance, supermarkets and mobile telecom. The analysis shows that market structure has a profound effect on customer satisfaction measurements and that this effect differs from industry to industry....... The paper concludes with an evaluation of the implications of the findings in relation to the use of results from customer satisfaction studies....

  9. Impacts of chemical gradients on microbial community structure

    DEFF Research Database (Denmark)

    Chen, Jianwei; Hanke, Anna; Tegetmeyer, Halina E

    2017-01-01

    Succession of redox processes is sometimes assumed to define a basic microbial community structure for ecosystems with oxygen gradients. In this paradigm, aerobic respiration, denitrification, fermentation and sulfate reduction proceed in a thermodynamically determined order, known as the 'redox ...... Journal advance online publication, 17 January 2017; doi:10.1038/ismej.2016.175....

  10. The Impact of Structural Adjustment on Training Needs.

    Science.gov (United States)

    Lucas, Robert E. B.

    1994-01-01

    During structural adjustment, training/retraining for unemployed persons is often poorly conceived. One reason is the lack of reliable ways to predict future skill requirements. Retraining should be kept fairly general to enable a wide range of potential jobs. (SK)

  11. Impact of Structured Movement Time on Preschoolers' Physical Activity Engagement

    Science.gov (United States)

    Palmer, Kara K.; Matsuyama, Abigail L.; Robinson, Leah E.

    2017-01-01

    Preschool-aged children are not meeting national physical activity recommendations. This study compares preschoolers' physical activity engagement during two different physical activity opportunities: outdoor free play or a structured movement session. Eighty-seven children served as participants: 40 children participated in outdoor free play and…

  12. Impact of Information Technology Governance Structures on Strategic Alignment

    Science.gov (United States)

    Gordon, Fitzroy R.

    2013-01-01

    This dissertation is a study of the relationship between Information Technology (IT) strategic alignment and IT governance structure within the organization. This dissertation replicates Asante (2010) among a different population where the prior results continue to hold, the non-experimental approach explored two research questions but include two…

  13. Impact of Information Technology Governance Structures on Strategic Alignment

    Science.gov (United States)

    Gordon, Fitzroy R.

    2013-01-01

    This dissertation is a study of the relationship between Information Technology (IT) strategic alignment and IT governance structure within the organization. This dissertation replicates Asante (2010) among a different population where the prior results continue to hold, the non-experimental approach explored two research questions but include two…

  14. Impact of Structured Movement Time on Preschoolers' Physical Activity Engagement

    Science.gov (United States)

    Palmer, Kara K.; Matsuyama, Abigail L.; Robinson, Leah E.

    2017-01-01

    Preschool-aged children are not meeting national physical activity recommendations. This study compares preschoolers' physical activity engagement during two different physical activity opportunities: outdoor free play or a structured movement session. Eighty-seven children served as participants: 40 children participated in outdoor free play and…

  15. The Rock Elm meteorite impact structure, Wisconsin: Geology and shock-metamorphic effects in quartz

    Science.gov (United States)

    French, B.M.; Cordua, W.S.; Plescia, J.B.

    2004-01-01

    The Rock Elm structure in southwest Wisconsin is an anomalous circular area of highly deformed rocks, ???6.5 km in diameter, located in a region of virtually horizontal undeformed sedimentary rocks. Shock-produced planar microstructures (PMs) have been identified in quartz grains in several lithologies associated with the structure: sandstones, quartzite pebbles, and breccia. Two distinct types of PMs are present: P1 features, which appear identical to planar fractures (PFs or cleavage), and P2 features, which are interpreted as possible incipient planar deformation features (PDFs). The latter are uniquely produced by the shock waves associated with meteorite impact events. Both types of PMs are oriented parallel to specific crystallographic planes in the quartz, most commonly to c(0001), ??112??2, and r/z101??1. The association of unusual, structurally deformed strata with distinct shock-produced microdeformation features in their quartz-bearing rocks establishes Rock Elm as a meteorite impact structure and supports the view that the presence of multiple parallel cleavages in quartz may be used independently as a criterion for meteorite impact. Preliminary paleontological studies indicate a minimum age of Middle Ordovician for the Rock Elm structure. A similar age estimate (450-400 Ma) is obtained independently by combining the results of studies of the general morphology of complex impact structures with estimated rates of sedimentation for the region. Such methods may be applicable to dating other old and deeply eroded impact structures formed in sedimentary target rocks.

  16. Research of hail impact on aircraft wheel door with lattice hybrid structure

    Science.gov (United States)

    Li, Shengze; Jin, Feng; Zhang, Weihua; Meng, Xuanzhu

    2016-09-01

    Aimed at a long lasting issue of hail impact on aircraft structures and aviation safety due to its high speed, the resistance performance of hail impact on the wheel door of aircraft with lattice hybrid structure is investigated. The proper anti-hail structure can be designed both efficiency and precision based on this work. The dynamic responses of 8 different sandwich plates in diverse impact speed are measured. Smoothed Particle Hydrodynamic (SPH) method is introduced to mimic the speciality of solid-liquid mixture trait of hailstone during the impact process. The deformation and damage degree of upper and lower panel of sandwich plate are analysed. The application range and failure mode for the relevant structure, as well as the energy absorbing ratio between lattice structure and aluminium foam are summarized. Results show that the tetrahedral sandwich plate with aluminium foam core is confirmed the best for absorbing energy. Furthermore, the high absorption characteristics of foam material enhance the capability of the impact resistance for the composition with lattice structure without increasing the structure surface density. The results of study are of worth to provide a reliable basis for reduced weight aircraft wheel door.

  17. Correlation and assessment of structural airplane crash data with flight parameters at impact

    Science.gov (United States)

    Carden, H. D.

    1982-01-01

    Crash deceleration pulse data from a crash dynamics program on general aviation airplanes and from transport crash data were analyzed. Structural airplane crash data and flight parameters at impact were correlated. Uncoupled equations for the normal and longitudinal floor impulses in the cabin area of the airplane were derived, and analytical expressions for structural crushing during impact and horizontal slide out were also determined. Agreement was found between experimental and analytical data for general aviation and transport airplanes over a relatively wide range of impact parameter. Two possible applications of the impulse data are presented: a postcrash evaluation of crash test parameters and an assumed crash scenario.

  18. The Karakul depression in Pamirs: The first impact structure in Central Asia

    Science.gov (United States)

    Gurov, E. P.; Gurova, H. P.; Rakitskaya, R. B.; Yamnichenko, A. YU.

    1993-01-01

    The Karakul depression was picked out as the possible impact structure by the study of space images of Tadjikistan. Its striking similarity with some complex impact craters such as Dellen and Gosses Bluff is evident. Our investigations of the Karakul depression in 1987 and 1989-1991 years allowed to determine it as the impact crater with the central uplift. The target of the crater is presented by slightly metamorphosed sedimentary rocks of Paleozoic, intensively folded and intruded with granites during the Gercynian orogeny. The modern structure of north-eastern Pamirs was formed by Alpinian orogeny; the raise of the area in Neogene was about 4000-7000 m.

  19. CHARACTERISTICS OF STRUCTURE OF IMPACT COPOLYMERS OF POLYPROPYLENE WITH LOW ETHYLENE CONTENTS

    Institute of Scientific and Technical Information of China (English)

    MA Dezhu; LI Xiqiang; ZHANG Ruiyun; HONG Kunlun; LUO Xiaolie

    1994-01-01

    In the present work, the structure and impact properties of copolymers of polypropylene with low ethylene contents have been investigated. Based on the results of 13C-NMR, FTIR,WAXD, DSC, PLM and SEM, the relationship between impact properties and morphology of the copolymers has been discussed. The high impact properties of copolymer ICP2 may attribute to the relatively higher ethylene content and homogeneous ethylene unit distribution. The size and its distribution of spherulite in the copolymers and cycloid cavities dispersed in polypropylene continue phase may also be two important factors which affect the impact properties of these materials.

  20. RESPONSE OF STRUCTURES TO HIGH VELOCITY IMPACTS: A GENERALIZED ALGORITHM

    Directory of Open Access Journals (Sweden)

    Aversh'ev Anatoliy Sergeevich

    2012-10-01

    Full Text Available In this paper, a high velocity impact produced by a spherical striker and a target are considered; different stages of loading and unloading, target deformations and propagation of non-stationary wave surfaces within the target are analyzed. The problem of the strike modeling and subsequent deformations is solved by using not only the equations of mechanics of deformable rigid bodies, but also fluid mechanics equations. The target material is simulated by means of an ideal "plastic gas". Modeling results and theoretical calculations are compared to the experimental results. The crater depth, its correlation with the striker diameter, values of the pressure and deformations of the target underneath the contact area are determined as the main characteristics of dynamic interaction.

  1. Team Structure and Scientific Impact of "Big Science" Research

    DEFF Research Database (Denmark)

    Lauto, Giancarlo; Valentin, Finn; Jeppesen, Jacob

    the facility and to an external university of research laboratory (secondments) out-perform all other types of institutional affiliations. ii.) Teams spanning multiple institutional types have the lowest performance. This is the case whether or not teams include resident scientists from Oak Ridge National...... Laboratories. iii.). Knowledge integration at the level of individual scientists clearly outperforms team level integration. iv.) Team diversity is associated with stronger performance in basic research than in applied research. Implications for the organisation of research collaboration of LSRFs...... of the Neutron Science Department of Oak Ridge National Laboratories in 2006-2009. Given the collaborative nature of research carried out at LSRFs, it is important to understand how its organization affects scientific impact. Diversity of teams along the institutional and cognitive dimensions affects both...

  2. ANALYSIS ON IMPACT RESPONSES OF UNRESTRAINED PLANAR FRAME STRUCTURE(Ⅱ)-NUMERICAL EXAMPLE ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    CHEN Rong; ZHENG Hai-tao; XUE Song-tao; TANG He-sheng

    2005-01-01

    By using the formula derived in Part (Ⅰ), the instant response of an unrestrained planar frame structure subjected to the impact of a moving rigid-body are evaluated and analysed.The impact force-time history between the structure and the moving rigid-body, shear force and bending moment distribution along the beams, axial force distribution along the bars were calculated. The wave propagation phenomena of the longitudinal wave in the bars, the flexural and shear waves in the beams were also analysed. The numerical results show that the time duration of impact force is controlled by the flexural wave and the longitudinal wave; the shear effect in beams should not be neglected in the impact response analysis of structures.

  3. Development of Time-Reversal Method for Impact Source Identification on Plate Structures

    Directory of Open Access Journals (Sweden)

    Chunlin Chen

    2013-01-01

    Full Text Available This paper presents a detailed study on the impact source identification of a plate structure using time-reversal (T-R method. Prior to impact monitoring, the plate is calibrated (or characterized by transfer functions at discrete locations on the plate surface. Both impact location and impact loading time-history are identified using T-R technique and associated signal processing algorithms. Numerical verification for finite-size isotropic plates under low velocity impacts is performed to demonstrate the versatility of T-R method for impact source identification. The tradeoff between accuracy of the impact location detection and calibration spacing is studied in detail. In particular, the effect of plate thickness on calibration spacing has been examined. A number of parameters selected for determining the impact location, approximated transfer functions and steps taken for reconstructing the impact loading time-history are also examined. Two types of noise with various intensities contaminated in strain response and/or transfer functions are investigated for demonstrating the stability and reliability of the T-R method. The results show that T-R method is robust against noise in impact location detection and force reconstruction in circumventing the inherent ill-conditioned inverse problem. Only transfer functions are needed to be calibrated and four sensors are requested in T-R method for impact identification.

  4. Gravitationally induced particle production and its impact on structure formation

    CERN Document Server

    Nunes, Rafael C

    2016-01-01

    In this paper we investigate the influence of a continuous particles creation processes on the linear and nonlinear matter clustering, and its consequences on the weak lensing effect induced by structure formation. We study the line of sight behavior of the contribution to the bispectrum signal at a given angular multipole $l$, showing that the scale where the nonlinear growth overcomes the linear effect depends strongly of particles creation rate.

  5. Blast and Impact Resistant Composite Structures for Navy Ships

    Science.gov (United States)

    2013-03-15

    Kinetic Energy of flying particles Beginning with the pioneering work by Mandelbrot et al. [1], numerous investigators have focused on statistical...affine [10]. Self affinity is defined and well-described in the context of fractals by Mandelbrot [2]. As the crack propagates, the scale of...manufactured by Larry Drzal’s group at Michigan State University—Composite Materials and Structures Center. References 1. Mandelbrot , B.B.; Passoja

  6. Structural and Functional Impacts of ER Coactivator Sequential Recruitment.

    Science.gov (United States)

    Yi, Ping; Wang, Zhao; Feng, Qin; Chou, Chao-Kai; Pintilie, Grigore D; Shen, Hong; Foulds, Charles E; Fan, Guizhen; Serysheva, Irina; Ludtke, Steven J; Schmid, Michael F; Hung, Mien-Chie; Chiu, Wah; O'Malley, Bert W

    2017-09-07

    Nuclear receptors recruit multiple coactivators sequentially to activate transcription. This "ordered" recruitment allows different coactivator activities to engage the nuclear receptor complex at different steps of transcription. Estrogen receptor (ER) recruits steroid receptor coactivator-3 (SRC-3) primary coactivator and secondary coactivators, p300/CBP and CARM1. CARM1 recruitment lags behind the binding of SRC-3 and p300 to ER. Combining cryo-electron microscopy (cryo-EM) structure analysis and biochemical approaches, we demonstrate that there is a close crosstalk between early- and late-recruited coactivators. The sequential recruitment of CARM1 not only adds a protein arginine methyltransferase activity to the ER-coactivator complex, it also alters the structural organization of the pre-existing ERE/ERα/SRC-3/p300 complex. It induces a p300 conformational change and significantly increases p300 HAT activity on histone H3K18 residues, which, in turn, promotes CARM1 methylation activity on H3R17 residues to enhance transcriptional activity. This study reveals a structural role for a coactivator sequential recruitment and biochemical process in ER-mediated transcription. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. The Impact of Geological Structures On The Gravity Field

    Science.gov (United States)

    Marti, U.

    In general, a uniform standard density value is used for the calculation of topographic effects for gravity field modelling in Switzerland. Only a limited number of promi- nent mass anomalies is treated with an individual density. In some regions this causes problems in predicting the surface gravity or the deflections of the vertical. An actual example is the construction of a new 57 km railway tunnel, where accurate deflec- tions of the vertical are needed for the orientation of gyroscope measurements. It was rather doubtful if our standard national gravity field model would fulfil the accuracy demands. Therefore, a refinement of the gravity field model was performed by digi- tising all the relevant geological structures in the vicinity of the planned tunnel. This lead to a 3D density model of irregularly shaped polyhedrons. Their influence on the gravity field (potential, gravity, deflections of the vertical and their first derivatives) are calculated rigorously. First results of this study are now available and reveal that the influences of the geological structures on the deflections of the vertical and on gravity are rather small (1 - 2 arcsec, 3 - 5 mgal) in the investigated region and they are at the limit of significance for the technical applications of levelling or gyroscope mea- surements. The largest effects are caused by quaternary sediments with a large density contrast and by some gneiss structures, which show only a small density contrast but their total mass can cause considerable anomalies in the gravity field.

  8. The Oasis impact structure, Libya: geological characteristics from ALOS PALSAR-2 data interpretation

    Science.gov (United States)

    van Gasselt, Stephan; Kim, Jung Rack; Choi, Yun-Soo; Kim, Jaemyeong

    2017-02-01

    Optical and infrared remote sensing may provide first-order clues for the identification of potential impact structures on the Earth. Despite the free availability of at least optical image data at highest resolution, research has shown that remote sensing analysis always remains inconclusive and extensive groundwork is needed for the confirmation of the impact origin of such structures. Commonly, optical image data and digital terrain models have been employed mainly for such remote sensing studies of impact structures. With the advent of imaging radar data, a few excursions have been made to also employ radar datasets. Despite its long use, capabilities of imaging radar for studying surface and subsurface structures have not been exploited quantitatively when applied for the identification and description of such features due to the inherent complexity of backscatter processes. In this work, we make use of higher-level derived radar datasets in order to gain clearer qualitative insights that help to describe and identify potential impact structures. We make use of high-resolution data products from the ALOS PALSAR-1 and ALOS PALSAR-2 L-band sensors to describe the heavily eroded Oasis impact structure located in the Libyan Desert. While amplitude radar data with single polarization have usually been utilized to accompany the suite of remote sensing datasets when interpreting impact structures in the past, we conclude that the integration of amplitude data with HH/HV/HH-HV polarization modes in standard and, in particular, in Ultra-Fine mode, as well as entropy-alpha decomposition data, significantly helps to identify and discriminate surface units based on their consolidation. Based on the overarching structural pattern, we determined the diameter of the eroded Oasis structure at 15.6 ± 0.5 km.

  9. Experiencing the Impact of Organizational Structure on Planning and Visioning Tasks

    Science.gov (United States)

    Pennisi, Lisa

    2012-01-01

    The various ways natural resource agencies and programs are structured and how that impacts leadership style and products is an important concept for students to understand. Leadership style and organizational structure determine visions, missions, goals and objectives that set the tone for organizations. This exercise demonstrates organizational…

  10. Experiencing the Impact of Organizational Structure on Planning and Visioning Tasks

    Science.gov (United States)

    Pennisi, Lisa

    2012-01-01

    The various ways natural resource agencies and programs are structured and how that impacts leadership style and products is an important concept for students to understand. Leadership style and organizational structure determine visions, missions, goals and objectives that set the tone for organizations. This exercise demonstrates organizational…

  11. Structural ambidexterity in NPD processes : A firm-level assessment of the impact of differentiated structures on innovation performance

    NARCIS (Netherlands)

    de Visser, Matthias; de Weerd-Nederhof, Petra; Faems, Dries; Song, Michael; van Looy, Bart; Visscher, Klaasjan

    2010-01-01

    Based on a survey study of 155 U.S. firms, we conducted a firm-level assessment of the impact of different kinds of structures (i.e., functional versus cross-functional) in different kinds of new product development (NPD) processes (i.e., incremental versus radical) on different kinds of firm innova

  12. The Impact of Embedded Story Structures versus Sequential Story Structures on Critical Thinking of Iranian Intermediate EFL Learners

    Directory of Open Access Journals (Sweden)

    Sara Samadi

    2016-09-01

    Full Text Available Confirming the constructive effects of reading comprehension on critical thinking, this paper attempted to investigate the impact of story structures on critical thinking of Iranian EFL learners. In doing so, the researcher utilized a quasi–experimental design with 60 intermediate students who were divided into two embedded story structures and sequential story structures groups (experimental groups. After taking PET, a critical thinking questionnaire was employed as a pre-test. The two groups received 16 sessions of treatment. All participants received similar amount of instruction but one group was given embedded short stories and the other group sequential short stories. To compare the two groups, they were received the parallel critical thinking questionnaire as a post-test. The two null hypotheses in this study were rejected due to different performance of the two groups. Statistical results did not support the superiority of neither structures. Therefore, the researcher was not able to suggest which structure caused a better or higher impact on critical thinking. However, the findings reveal that teaching story structures in EFL context can develop critical thinking of intermediate EFL learners. The study have some implications for test-designers, teachers, and students. Keywords: Critical thinking, Embedded story structure, Sequential story structure, Reading comprehension

  13. Communication Breakdown: The Impact of Ageing on Synapse Structure

    Science.gov (United States)

    Petralia, Ronald S.; Mattson, Mark P.; Yao, Pamela J.

    2014-01-01

    Impaired synaptic plasticity is implicated in the functional decline of the nervous system associated with ageing. Understanding the structure of ageing synapses is essential to understanding the functions of these synapses and their role in the ageing nervous system. In this review, we summarize studies on ageing synapses in vertebrates and invertebrates, focusing on changes in morphology and ultrastructure. We cover different parts of the nervous system, including the brain, the retina, the cochlea, and the neuromuscular junction. The morphological characteristics of aged synapses could shed light on the underlying molecular changes and their functional consequences. PMID:24495392

  14. Characterisation of fluid-structure interaction for water impact of composite panels

    Directory of Open Access Journals (Sweden)

    M Battley

    2016-09-01

    Full Text Available Hydrodynamic loads can be very significant for high performance marine vessels. Water impact of panels, known as "slamming", typically generates high magnitude short duration pressure pulses that move across the structure. In the case of compliant panels there can be significant coupling between the pressures and the structural responses. While there has been significant development of numerical methods to simulate this type of fluid-structure interaction there is only very limited experimental data available for validation of the simulation approaches. This paper describes an experimental study of sandwich composite panels subjected to water slamming impacts. The results demonstrate that compliant panels subjected to water slamming impacts experience different pressures than rigid panels, and have different structural responses than predicted by traditional uniform pressure based analysis approaches. The study also characterizes the significant effects that the dimensions of pressure transducers and data acquisition sampling rates have on the measured pressures.

  15. Evaluating the impact of investments in information technology on structural inertia in health organizations.

    Science.gov (United States)

    Bewley, Lee W

    2010-01-01

    Structural inertia is the overall capacity of an organization to adapt within a market environment. This paper reviews the impact of healthcare investments in information management/information technology (IM/IT) on the strategic management concept of structural inertia. Research indicates that healthcare executives should consider the relative state of structural inertia for their firms and match them with potential IM/IT solutions. Additionally, organizations should favorably consider IM/IT solutions that are comparatively less complex.

  16. Damage criticality and inspection concerns of composite-metallic aircraft structures under blunt impact

    Science.gov (United States)

    Zou, D.; Haack, C.; Bishop, P.; Bezabeh, A.

    2015-04-01

    Composite aircraft structures such as fuselage and wings are subject to impact from many sources. Ground service equipment (GSE) vehicles are regarded as realistic sources of blunt impact damage, where the protective soft rubber is used. With the use of composite materials, blunt impact damage is of special interest, since potential significant structural damage may be barely visible or invisible on the structure's outer surface. Such impact can result in local or non-local damage, in terms of internal delamination in skin, interfacial delamination between stiffeners and skin, and fracture of internal reinforced component such as stringers and frames. The consequences of these events result in aircraft damage, delays, and financial cost to the industry. Therefore, it is necessary to understand the criticality of damage under this impact and provide reliable recommendations for safety and inspection technologies. This investigation concerns a composite-metallic 4-hat-stiffened and 5-frame panel, designed to represent a fuselage structure panel generic to the new generation of composite aircraft. The test fixtures were developed based on the correlation between finite element analyses of the panel model and the barrel model. Three static tests at certain amount of impact energy were performed, in order to improve the understanding of the influence of the variation in shear ties, and the added rotational stiffness. The results of this research demonstrated low velocity high mass impacts on composite aircraft fuselages beyond 82.1 kN of impact load, which may cause extensive internal structural damage without clear visual detectability on the external skin surface.

  17. The Keurusselkä impact structure, Finland-Impact origin confirmed by characterization of planar deformation features in quartz grains

    Science.gov (United States)

    Ferrière, Ludovic; Raiskila, Selen; Osinski, Gordon R.; Pesonen, Lauri J.; Lehtinen, Martti

    2010-03-01

    Although the meteorite impact origin of the Keurusselkä impact structure (central Finland) has been established on the basis of the occurrence of shatter cones, no detailed microscopic examination of the impactites from this structure has so far been made. Previous microscope investigations of in situ rocks did not yield any firm evidence of shock features (Raiskila et al. 2008; Kinnunen and Hietala 2009). We have carried out microscopic observations on petrographic thin sections from seven in situ shatter cone samples and report here the discovery of planar fractures (PFs) and planar deformation features (PDFs) in quartz and feldspar grains. The detection and characterization of microscopic shock metamorphic features in the investigated samples substantiates a meteorite impact origin for the Keurusselkä structure. The crystallographic orientations of 372 PDF sets in 276 quartz grains were measured, using a universal stage (U-stage) microscope, for five of the seven distinct shatter cone samples. Based on our U-stage results, we estimate that investigated shatter cone samples from the Keurusselkä structure have experienced peak shock pressures from approximately 2 GPa to slightly less than 20 GPa for the more heavily shocked samples. The decoration of most of the PDFs with fluid inclusions also indicates that these originally amorphous shock features were altered by postimpact processes. Finally, our field observations indicate that the exposed surface corresponds to the crater floor; it is, however, difficult to estimate the exact diameter of the structure and the precise amount of material that has been eroded since its formation.

  18. Impact of Aerodynamics and Structures Technology on Heavy Lift Tiltrotors

    Science.gov (United States)

    Acree, C. W., Jr.

    2006-01-01

    Rotor performance and aeroelastic stability are presented for a 124,000-lb Large Civil Tilt Rotor (LCTR) design. It was designed to carry 120 passengers for 1200 nm, with performance of 350 knots at 30,000 ft altitude. Design features include a low-mounted wing and hingeless rotors, with a very low cruise tip speed of 350 ft/sec. The rotor and wing design processes are described, including rotor optimization methods and wing/rotor aeroelastic stability analyses. New rotor airfoils were designed specifically for the LCTR; the resulting performance improvements are compared to current technology airfoils. Twist, taper and precone optimization are presented, along with the effects of blade flexibility on performance. A new wing airfoil was designed and a composite structure was developed to meet the wing load requirements for certification. Predictions of aeroelastic stability are presented for the optimized rotor and wing, along with summaries of the effects of rotor design parameters on stability.

  19. Synthesis and Structure Control of A New Kind of Inelastomer Impact Modifier with Core-shell Structure and Impact Modification to PVC/CPE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new kind of inelastomer impact modifier with a core-shell structure was synthesized by employing a multi-step composite emulsion polymerization technique, the size and morphology structure of the core-shell particles could be controlled by the multi-step composite emulsion polymerization technique. The study of the impact strength and the elongation at break of the PVC/CPE blend with different contents of core-shell particles(C-S) indicated that the mechanical properties of PVC/CPE/C-S composite were the best when the concentration of the particle was 2.5%(mass fraction) which showed the different regularities and characteristics of elastomer toughening plastic.

  20. Local Impact Simulation of SC Wall Structures using Aircraft Engine Projectile

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chulhun; Lee, Jungwhee; Lee, Hanjoo [Dankook Univ., Yongin (Korea, Republic of); Jung, Raeyoung; Hyun, Changhun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-05-15

    SC wall structure developed for nuclear power plant buildings consists of plain concrete and two steel plates on both surface of the concrete, while RC structure consists of re bar and concrete. SC structure has higher scabbing resistance than RC structure due to the action of steel plate on the rear side of impact. Therefore SC structure is known as more effective structure from the viewpoint of aircraft crash than RC structure. However, most of the recent researches and experiments about local impact damage deal with RC structures, and the effect of re bar and steel plate is not considered reasonably. Although Walter et al. and Make-work et al. suggested a formula for evaluating perforation depth of steel plate covered RC walls, most of the previous researches about SC structure are focused on perforation and scabbing due to the impact of hard projectile, rather than soft projectile such as an aircraft. In this research a soft projectile, i. e. aircraft engine, is utilized for impact simulation of RC and SC walls. To evaluate local damage of SC wall structures, parametric study with the variables of wall thickness and steel ratio of the cover plate is performed, and the results are compared with those of RC structures. Since scabbing was prevented by the steel plates, penetration mode of damage was observed in SC walls while scabbing damage was occurred in RC walls. It is confirmed that the rear steel plate not only contains concrete debris, but also reduces the internal damage of the concrete walls. Penetration depth of SC walls did not largely vary due to the increasing steel ratio, and similar results to RC walls were observed when the wall thickness is larger than a certain value since the impact resistance of SC wall is mainly governed by the thickness of concrete part. Therefore, it is expected that similar level of impact resistance to RC structure can be produced with the minimum thickness of steel plates of SC structure. According to these results, SC

  1. Evaluation of the Impact of the EU Structural Support on the Competitiveness of Lithuanian Economics

    Directory of Open Access Journals (Sweden)

    Rita Remeikiene

    2016-06-01

    Full Text Available Increasing amounts of the EU structural support in Lithuania require theoretical and practical research to disclose the determinants that have a significant impact on the competitiveness of Lithuanian economics. The purpose of this article is to evaluate the impact of the EU structural support on the competitiveness of Lithuanian economics. The methods of the research include systematic and comparative analysis of the scientific literature, expert evaluation and linear regression. The research disclosed the main determinants of country’s competitiveness. The results have revealed that EU structural support has the most significant impact on Lithuanian engineering and technological infrastructure. The impact of the support on country’s macroeconomic, scientific and social environment can also be considered as significant. The EU structural support has medium strong impact on education and business environment conditions in Lithuania. It has been established that, in the field of business advancement, Lithuanian should be rated as medium competitive. Hence, the increase in country’s competitiveness by employing EU structural funds should be treated as one of priority aims. In addition, responsible authorities should perform with higher efficiency seeking for higher competitiveness of the country.

  2. Workplace experience of radiographers: impact of structural and interpersonal interventions.

    Science.gov (United States)

    Kubik-Huch, R A; Klaghofer, R; Römpler, M; Weber, A; Buddeberg-Fischer, B

    2010-02-01

    Within the framework of organisational development, an assessment of the workplace experience of radiographers (RGs) was conducted. The aims of this study were to develop structural and interpersonal interventions and to prove their effectiveness and feasibility. A questionnaire consisting of work-related factors, e.g. time management and communication, and two validated instruments (Workplace Analysis Questionnaire, Effort-Reward Imbalance Scale) was distributed to all RGs (n = 33) at baseline (T1). Interventions were implemented and a follow-up survey (T2) was performed 18 months after the initial assessment. At T1, areas with highest dissatisfaction were communication and time management for ambulant patients (bad/very bad, 57% each). The interventions addressed adaptation of work plans, coaching in developing interpersonal and team leadership skills, and regular team meetings. The follow-up survey (T2) showed significantly improved communication and cooperation within the team and improved qualification opportunities, whereas no significant changes could be identified in time management and in the workplace-related scales 'effort' expended at work and 'reward' received in return for the effort. Motivating workplace experience is important for high-level service quality and for attracting well-qualified radiographers to work at a place and to stay in the team for a longer period.

  3. Network structure impacts global commodity trade growth and resilience

    Science.gov (United States)

    Rovenskaya, Elena; Fath, Brian D.

    2017-01-01

    Global commodity trade networks are critical to our collective sustainable development. Their increasing interconnectedness pose two practical questions: (i) Do the current network configurations support their further growth? (ii) How resilient are these networks to economic shocks? We analyze the data of global commodity trade flows from 1996 to 2012 to evaluate the relationship between structural properties of the global commodity trade networks and (a) their dynamic growth, as well as (b) the resilience of their growth with respect to the 2009 global economic shock. Specifically, we explore the role of network efficiency and redundancy using the information theory-based network flow analysis. We find that, while network efficiency is positively correlated with growth, highly efficient systems appear to be less resilient, losing more and gaining less growth following an economic shock. While all examined networks are rather redundant, we find that network redundancy does not hinder their growth. Moreover, systems exhibiting higher levels of redundancy lose less and gain more growth following an economic shock. We suggest that a strategy to support making global trade networks more efficient via, e.g., preferential trade agreements and higher specialization, can promote their further growth; while a strategy to increase the global trade networks’ redundancy via e.g., more abundant free-trade agreements, can improve their resilience to global economic shocks. PMID:28207790

  4. Workplace experience of radiographers: impact of structural and interpersonal interventions

    Energy Technology Data Exchange (ETDEWEB)

    Kubik-Huch, R.A.; Roempler, M.; Weber, A. [Kantonsspital Baden, Institute of Radiology, Baden (Switzerland); Klaghofer, R.; Buddeberg-Fischer, B. [Zurich University Hospital, Department of Psychosocial Medicine, Zurich (Switzerland)

    2010-02-15

    Within the framework of organisational development, an assessment of the workplace experience of radiographers (RGs) was conducted. The aims of this study were to develop structural and interpersonal interventions and to prove their effectiveness and feasibility. A questionnaire consisting of work-related factors, e.g. time management and communication, and two validated instruments (Workplace Analysis Questionnaire, Effort-Reward Imbalance Scale) was distributed to all RGs (n = 33) at baseline (T1). Interventions were implemented and a follow-up survey (T2) was performed 18 months after the initial assessment. At T1, areas with highest dissatisfaction were communication and time management for ambulant patients (bad/very bad, 57% each). The interventions addressed adaptation of work plans, coaching in developing interpersonal and team leadership skills, and regular team meetings. The follow-up survey (T2) showed significantly improved communication and cooperation within the team and improved qualification opportunities, whereas no significant changes could be identified in time management and in the workplace-related scales 'effort' expended at work and 'reward' received in return for the effort. Motivating workplace experience is important for high-level service quality and for attracting well-qualified radiographers to work at a place and to stay in the team for a longer period. (orig.)

  5. Geophysical characterization of two circular structures at Bajada del Diablo (Patagonia, Argentina): Indication of impact origin

    Science.gov (United States)

    Prezzi, Claudia B.; Orgeira, María Julia; Acevedo, Rogelio D.; Ponce, Juan Federico; Martinez, Oscar; Rabassa, Jorge O.; Corbella, Hugo; Vásquez, Carlos; González-Guillot, Mauricio; Subías, Ignacio

    2012-02-01

    An impact origin has been proposed for the circular structures found in Bajada del Diablo, Patagonia, Argentina. Taking into account its extension and the number of impact structures, Bajada del Diablo would be the largest meteoritic impact areas known on Earth, being an extremely interesting area for the research of impact events and processes. Moreover, the global distribution of known impact structures shows a surprising asymmetry. Particularly, South America has only seven described areas. It is evident that this situation is an artifact, highlighting the importance of intensifying the research in the least studied areas such as Argentina. Circular structures in Bajada del Diablo have been identified on two rock types: the Quiñelaf eruptive complex and Pampa Sastre Formation. In the first case, circular structures are placed in olivine basalts. On the other hand, Pampa Sastre Formation (late Pliocene/early Pleistocene) corresponds to conglomerate layers with basalt clasts boulder and block in size in a coarse sandy matrix. With the aim of further the investigation of the proposed impact origin for these circular structures, we carried out detailed topographic, magnetic and electromagnetic ground surveys in two circular structures ("8" and "A") found in Pampa Sastre conglomerates. Both circular structures are simple, bowl-shaped with rim diameters of 300 m and maximum depths of 10 m. They have been partially filled in by debris flows from the rims and wind-blown sands. Two preliminary magnetic profiles have also been carried out in circular structure "G" found in Quiñelaf basalts. The magnetic anomalies show a circular pattern with a slightly negative and relatively flat signal in the circular structures' bases. Furthermore in the circular structures' rims, high-amplitude, conspicuous and localized (short wavelength) anomalies are observed. Such large amplitude and short wavelength anomalies are not detected outside the circular structures. For all used

  6. The convincing identification of terrestrial meteorite impact structures: What works, what doesn't, and why

    Science.gov (United States)

    French, Bevan M.; Koeberl, Christian

    2010-01-01

    In the geological sciences it has only recently been recognized how important the process of impact cratering is on a planetary scale, where it is commonly the most important surface-modifying process. On the Moon and other planetary bodies that lack an appreciable atmosphere, meteorite impact craters are well preserved, and they can commonly be recognized from morphological characteristics, but on Earth complications arise as a consequence of the weathering, obliteration, deformation, or burial of impact craters and the projectiles that formed them. These problems made it necessary to develop diagnostic criteria for the identification and confirmation of impact structures on Earth. Diagnostic evidence for impact events is often present in the target rocks that were affected by the impact. The conditions of impact produce an unusual group of melted, shocked, and brecciated rocks, some of which fill the resulting crater, and others which are transported, in some cases to considerable distances from the source crater. Only the presence of diagnostic shock-metamorphic effects and, in some cases, the discovery of meteorites, or traces thereof, is generally accepted as unambiguous evidence for an impact origin. Shock deformation can be expressed in macroscopic form (shatter cones) or in microscopic forms (e.g., distinctive planar deformation features [PDFs] in quartz). In nature, shock-metamorphic effects are uniquely characteristic of shock levels associated with hypervelocity impact. The same two criteria (shock-metamorphic effects or traces of the impacting meteorite) apply to distal impact ejecta layers, and their presence confirms that materials found in such layers originated in an impact event at a possibly still unknown location. As of 2009 about 175 impact structures have been identified on Earth based on these criteria. A wide variety of shock-metamorphic effects has been identified, with the best diagnostic indicators for shock metamorphism being features

  7. Generating spatial precipitation ensembles: impact of temporal correlation structure

    Directory of Open Access Journals (Sweden)

    O. Rakovec

    2012-09-01

    Full Text Available Sound spatially distributed rainfall fields including a proper spatial and temporal error structure are of key interest for hydrologists to force hydrological models and to identify uncertainties in the simulated and forecasted catchment response. The current paper presents a temporally coherent error identification method based on time-dependent multivariate spatial conditional simulations, which are conditioned on preceding simulations. A sensitivity analysis and real-world experiment are carried out within the hilly region of the Belgian Ardennes. Precipitation fields are simulated for pixels of 10 km × 10 km resolution. Uncertainty analyses in the simulated fields focus on (1 the number of previous simulation hours on which the new simulation is conditioned, (2 the advection speed of the rainfall event, (3 the size of the catchment considered, and (4 the rain gauge density within the catchment. The results for a sensitivity analysis show for typical advection speeds >20 km h−1, no uncertainty is added in terms of across ensemble spread when conditioned on more than one or two previous hourly simulations. However, for the real-world experiment, additional uncertainty can still be added when conditioning on a larger number of previous simulations. This is because for actual precipitation fields, the dynamics exhibit a larger spatial and temporal variability. Moreover, by thinning the observation network with 50%, the added uncertainty increases only slightly and the cross-validation shows that the simulations at the unobserved locations are unbiased. Finally, the first-order autocorrelation coefficients show clear temporal coherence in the time series of the areal precipitation using the time-dependent multivariate conditional simulations, which was not the case using the time-independent univariate conditional simulations. The presented work can be easily implemented within a hydrological calibration and data assimilation

  8. Impact Resistance of Structural Ceramics. Part 1. Instrumented Drop- Weight Tests

    Science.gov (United States)

    1976-05-01

    instrumented Charpy test and the instrumented DWT. The Impact Fracture Energy of a ceramic is determined by its dynamic strength. At room temperature...AFML-TR-76-56 ~I’S PART I 0 IMPACT RESISTANCE OF STRUCTURAL CERAMICS PART I: INSTRUMENTED DROP-WEIGHT TESTS PROCESSING AND HIGH TEMPERATURE MATERIALS...BLAG..OTP ,fIJMED .. TABLE OF CONTENTS SECTION PAGE I INTRODUCTION 1 II DROP-WEIGHT TEST (DWT) 3 III EXPERIMENTAL PROCEDURES FOR THE INSTRUMENTED DWT AT

  9. The Chesapeake Bay crater: geology and geophysics of a Late Eocene submarine impact structure

    Science.gov (United States)

    Poag, C. Wylie; Koeberl, Christian; Reimold, Wolf Uwe

    2004-01-01

    The list of impact craters documented on Earth is short. Only about 165 genuine impact structures have been identified to date (Table 1.1). Even so, the number is steadily increasing at the rate of ∼3–5 per year (Grieve et al. 1995; Earth Impact Database at http://www.unb.ca/passc/Impact/Database/). In stark contrast, most other rocky planets and satellites of our solar system are pockmarked by thousands to hundreds of thousands of impact features (Beatty et al. 1999). Nevertheless, impact specialists acknowledge that Earth, too, has undergone billions of years of bolide bombardment (Melosh 1989; Schoenberg et al. 2002). The most intense bombardment, however, took place during Earth’s earliest history (∼3.8–4 Ga; Ryder 1990; Cohen et al. 2000; Ryder et al. 2000). Traces of most terrestrial impacts have been completely erased or strongly altered by the dynamic processes of a thick atmosphere, deep ocean, and mobile crust, a combination unique to our planet. Planetary geologists now recognize that processes associated with bolide impacts are fundamental to planetary accretion and surface modification (Melosh 1989; Peucker-Ehrenbrink and Schmitz 2001). Incoming meteorites may have been primary sources for Earth’s water, and, perhaps, even organic life as we know it (Thomas et al. 1997; Kring 2000). There is little doubt that impacts played a major role in the evolution of Earth’s biota (Ryder et al. 1996; Hart 1996).

  10. Energy Analysis for TMD-Structure Systems Subjected to Impact Loading

    Institute of Scientific and Technical Information of China (English)

    王树青; 李华军; 嵇春艳; 焦桂英

    2002-01-01

    This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper(TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysis focnses on theenergy concept of TMD/structure systems. In this study, a time domain is taken. The platform is modeled as a simplifiedsingle-degree-of-freedom (SDOF) system by extraction of the first vibration mode of the structure and the excited force isassumed to be impact loading. The energy dissipation and energy transmission of the structure-TMD system are studied.Finally, an optimized TMD design for the modeled platform is demonstrated based on a new type of cost function - maxi-mum dissipated energy by TMD. Results indicate that TMD control is effective in reducing the standard deviation of thedeck motion but less effective in reducing the maximum response under impact loading.

  11. Flynn Creek Impact Structure: New Insights from Breccias, Melt Features, Shatter Cones, and Remote Sensing

    Science.gov (United States)

    Evenick, J. C.; Lee, P.; Deane, B.

    2004-01-01

    The Flynn Creek impact structure is located in Tennessee, USA (36 deg.17 min.N, 85 deg.40 min.W). The structure was first mapped as a crypto-volcanic by Wilson and Born in 1936 [1]. Although they did not properly identify the stratigraphy within the crater or the causal mechanism, they did correctly define the horizontal extent of the crater. More detailed surface and subsurface research by Roddy (1979) accurately described the crater as being an impact structure with a diameter of 3.8 km. It formed around 360 Ma, which corresponds to the interval between the deposition of the Nashville Group and the Chattanooga Shale. Although there is limited rock outcrop in the area, there are exposed surface faults, folds, and large outcrops of impact breccia within the crater.

  12. Augmented Reality to Support On-Field Post-Impact Maintenance Operations on Thin Structures

    Directory of Open Access Journals (Sweden)

    Luca De Marchi

    2013-01-01

    monitored and a signal processing algorithm (the Warped Frequency Transform able to compensate for dispersion the acquired waveforms. The compensated waveforms yield to a robust estimation of Lamb waves difference in distance of propagation (DDOP, used to feed hyperbolic algorithms for impact location determination, and allow an estimation of the uncertainty of the impact positioning as well as of the impact energy. The outputs of the impact methodology are passed to a visualization technology that yielding their representation in Augmented Reality (AR is meant to support the inspector during the on-field inspection/diagnosis as well as the maintenance operations. The inspector, in fact, can see interactively in real time the impact data directly on the surface of the structure. To validate the proposed approach, tests on an aluminum plate are presented. Results confirm the feasibility of the method and its exploitability in maintenance practice.

  13. CIRIR Programs: Drilling and Research Opportunities at the Rochechouart Impact Structure

    Science.gov (United States)

    Lambert, P.; Alwmark, C.; Baratoux, D.; Brack, A.; Bruneton, P.; Buchner, E.; Claeys, P.; Dence, M.; French, B.; Hoerz, F

    2017-01-01

    Owing to its size, accessibility and erosional level, the Rochechouart impact structure, dated at 203 +/- 2 Ma (recalc.), is a unique reser-voir of knowledge within the population of the rare terrestrial analogous to large impacts craters observed on planetary surfaces. The site gives direct access to fundamental mechanisms both in impact-related geology (origin and evolution of planets) and biology (habitability of planets, emergence and evolution of life). For the last decade P. Lambert has been installing Rochechouart as International Natural Laboratory for studying impact processes and collateral effects on planetary surfaces. For this purpose the Center for International Research on Impacts and on Rochechouart (CIRIR) was installed on site in 2016 with twofold objectives and activities. First ones are scientific and dedicated to the scientific community. The second are cultural and educational and are dedi-cated to the public sensu lato. We present here the CIRIR, its scientific programs and the related reseach opportunities.

  14. Shatter cones at the Keurusselkä impact structure and their relation to local jointing

    Science.gov (United States)

    Hasch, Maximilian; Reimold, Wolf Uwe; Raschke, Ulli; Zaag, Patrice Tristan

    2016-08-01

    Shatter cones are the only distinct meso- to macroscopic recognition criterion for impact structures, yet not all is known about their formation. The Keurusselkä impact structure, Finland, is interesting in that it presents a multitude of well-exposed shatter cones in medium- to coarse-grained granitoids. The allegedly 27 km wide Keurusselkä impact structure was formed about 1150 Ma ago in rocks of the Central Finland Granitoid Complex. Special attention was paid in this work to possible relationships between shatter cones and local, as well as regionally occurring, fracture or joint systems. A possible shatter cone find outside the previously suggested edge of the structure could mean that the Keurusselkä impact structure is larger than previously thought. The spacing between joints/fractures from regional joint systems was influenced by the impact, but impact-induced fractures strongly follow the regional joint orientation trends. There is a distinct relationship between shatter cones and joints: shatter cones occur on and against joint surfaces of varied orientations and belonging to the regional orientation trends. Planar fractures (PF) and planar deformation features (PDF) were found in three shatter cone samples from the central-most part of the impact structure, whereas other country rock samples from the same level of exposure but further from the assumed center lack shock deformation features. PDF occurrence is enhanced within 5 mm of shatter cone surfaces, which is interpreted to suggest that shock wave reverberation at preimpact joints could be responsible for this local enhancement of shock deformation. Some shatter cone surfaces are coated with a quasi-opaque material which is also found in conspicuous veinlets that branch off from shatter cone surfaces and resemble pseudotachylitic breccia veins. The vein-filling is composed of two mineral phases, one of which could be identified as a montmorillonitic phyllosilicate. The second phase could not be

  15. The Peerless structure, Daniels County, northeastern Montana: A probable late Ordovician impact structure

    Science.gov (United States)

    Comstock, J. M.; Dietz, R. D.; Morrow, J. R.

    2004-05-01

    The Peerless structure is an ~6 km-diameter sub-surface anomaly located in Daniels County, northeastern Montana. The disruption of sedimentary rock in the structure lies between 2624 to 2818 m below the topographic surface. Seismic mapping shows a typical complex crater composed of a central uplift ~2 km across, which shows structural uplift of up to 90 m, an annular ring ~4 km across, and an outer rim ~6 km in diameter. The youngest disrupted rock unit is the upper Ordovician Red River formation, which indicates that the structure was formed about 430-450 Ma ago.

  16. Low-Cost Impact Detection and Location for Automated Inspections of 3D Metallic Based Structures

    Directory of Open Access Journals (Sweden)

    Carlos Morón

    2015-05-01

    Full Text Available This paper describes a new low-cost means to detect and locate mechanical impacts (collisions on a 3D metal-based structure. We employ the simple and reasonably hypothesis that the use of a homogeneous material will allow certain details of the impact to be automatically determined by measuring the time delays of acoustic wave propagation throughout the 3D structure. The location of strategic piezoelectric sensors on the structure and an electronic-computerized system has allowed us to determine the instant and position at which the impact is produced. The proposed automatic system allows us to fully integrate impact point detection and the task of inspecting the point or zone at which this impact occurs. What is more, the proposed method can be easily integrated into a robot-based inspection system capable of moving over 3D metallic structures, thus avoiding (or minimizing the need for direct human intervention. Experimental results are provided to show the effectiveness of the proposed approach.

  17. Low-Cost Impact Detection and Location for Automated Inspections of 3D Metallic Based Structures

    Science.gov (United States)

    Morón, Carlos; Portilla, Marina P.; Somolinos, José A.; Morales, Rafael

    2015-01-01

    This paper describes a new low-cost means to detect and locate mechanical impacts (collisions) on a 3D metal-based structure. We employ the simple and reasonably hypothesis that the use of a homogeneous material will allow certain details of the impact to be automatically determined by measuring the time delays of acoustic wave propagation throughout the 3D structure. The location of strategic piezoelectric sensors on the structure and an electronic-computerized system has allowed us to determine the instant and position at which the impact is produced. The proposed automatic system allows us to fully integrate impact point detection and the task of inspecting the point or zone at which this impact occurs. What is more, the proposed method can be easily integrated into a robot-based inspection system capable of moving over 3D metallic structures, thus avoiding (or minimizing) the need for direct human intervention. Experimental results are provided to show the effectiveness of the proposed approach. PMID:26029951

  18. Geology and impact features of Riachão structure, northern Brazil

    Science.gov (United States)

    Maziviero, Mariana V.; Vasconcelos, Marcos A. R.; Crósta, Alvaro P.; Góes, Ana M.; Reimold, Wolf U.; de C. Carneiro, Cleyton

    2013-10-01

    Riachão, located at S7°42'/W46°38' in Maranhão State, northeastern Brazil, is a complex impact structure of about 4.1 km diameter, formed in Pennsylvanian to Permian sedimentary rocks of the Parnaíba Basin sequence. Although its impact origin was already proposed in the 1970s, information on its geology and shock features is still scarce in the literature. We present here the main geomorphological and geological characteristics of the Riachão impact structure obtained by integrated geophysical and remote sensing analysis, as well as geological field work and petrographic analysis. The identified lithostratigraphic units consist of different levels of the Pedra de Fogo Formation and, possibly, the Piauí Formation. Our petrographic analysis confirms the presence of shock-diagnostic planar microdeformation structures in quartz grains of sandstone from the central uplift as evidence for an impact origin of the Riachão structure. The absence of crater-filling impact breccias and melt rocks, shatter cones, as well as the restricted occurrence of microscopic shock effects, suggests that intense and relatively deep erosion has occurred since crater formation.

  19. Impact localization on composite structures using time difference and MUSIC approach

    Science.gov (United States)

    Zhong, Yongteng; Xiang, Jiawei

    2017-05-01

    1-D uniform linear array (ULA) has the shortcoming of the half-plane mirror effect, which does not allow discriminating between a target placed above the array and a target placed below the array. This paper presents time difference (TD) and multiple signal classification (MUSIC) based omni-directional impact localization on a large stiffened composite structure using improved linear array, which is able to perform omni-directional 360° localization. This array contains 2M+3 PZT sensors, where 2M+1 PZT sensors are arranged as a uniform linear array, and the other two PZT sensors are placed above and below the array. Firstly, the arrival times of impact signals observed by the other two sensors are determined using the wavelet transform. Compared with each other, the direction range of impact source can be decided in general, 0°to 180° or 180°to 360°. And then, two dimensional multiple signal classification (2D-MUSIC) based spatial spectrum formula using the uniform linear array is applied for impact localization by the general direction range. When the arrival times of impact signals observed by upper PZT is equal to that of lower PZT, the direction can be located in x axis (0°or 180°). And time difference based MUSIC method is present to locate impact position. To verify the proposed approach, the proposed approach is applied to a composite structure. The localization results are in good agreement with the actual impact occurring positions.

  20. The Impact of Organizational Structure on Internal and External Integration: An empirical, cross-regional assessment

    Directory of Open Access Journals (Sweden)

    Xenophon Koufteros

    2014-06-01

    Full Text Available We examine the effects of organizational structure on cross-functional integration, supplier integration, and customer integration and assess whether such effects vary by geographical region. Specifically, we investigate the impact of centralization, formalization, and complexity on both internal (cross-functional and external (supplier, customer integration. Relationships are examined across Western and East Asian environments using data collected from 238 manufacturing plants in eight countries. We find that structural features have differing impacts on cross-functional, supplier, and customer integration, and these effects vary across geographical regions.

  1. An historical perspective on the suspected meteorite impact sites of Tennessee. 2: The Howell Structure

    Science.gov (United States)

    Ford, J. R. H.; Orchiston, Wayne; Clendening, Ron

    2015-03-01

    The Howell Structure is a suspected meteorite impact site in Tennessee, USA, and came to the attention of geologists during the 1930s. It was first investigated by Born and Wilson in 1937, and the few subsequent investigations that have occurred at this extensively eroded site have revealed the presence of breccias and the possible existence of shatter cones. However, cores drilled in the 1960s have recently been analyzed, and these provide evidence of shock metamorphism, suggesting that the Howell Structure is the eroded scar of a meteorite impact.

  2. Shatter Cones and Associated Shock-Metamorphic Microdeformations in Minerals - The Case of the Sudbury Impact Structure, Canada

    Science.gov (United States)

    Ferrière, L.; Osinski, G. R.

    2013-08-01

    Shatter cones are the only diagnostic evidence of hypervelocity impact that develop on a macro- to megascopic scale. We report here on new macroscopic and petrographic investigations of shatter cone samples from the Sudbuy impact structure (Canada).

  3. Impact of structural aging on seismic risk assessment of reinforced concrete structures in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Ellingwood, B.; Song, J. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

    1996-03-01

    The Structural Aging Program is addressing the potential for degradation of concrete structural components and systems in nuclear power plants over time due to aging and aggressive environmental stressors. Structures are passive under normal operating conditions but play a key role in mitigating design-basis events, particularly those arising from external challenges such as earthquakes, extreme winds, fires and floods. Structures are plant-specific and unique, often are difficult to inspect, and are virtually impossible to replace. The importance of structural failures in accident mitigation is amplified because such failures may lead to common-cause failures of other components. Structural condition assessment and service life prediction must focus on a few critical components and systems within the plant. Components and systems that are dominant contributors to risk and that require particular attention can be identified through the mathematical formalism of a probabilistic risk assessment, or PRA. To illustrate, the role of structural degradation due to aging on plant risk is examined through the framework of a Level 1 seismic PRA of a nuclear power plant. Plausible mechanisms of structural degradation are found to increase the core damage probability by approximately a factor of two.

  4. Soft impact testing of a wall-floor-wall reinforced concrete structure

    Energy Technology Data Exchange (ETDEWEB)

    Vepsä, Ari, E-mail: ari.vepsa@vtt.fi; Calonius, Kim; Saarenheimo, Arja; Aatola, Seppo; Halonen, Matti

    2017-01-15

    Highlights: • A wall-floor-wall reinforced concrete structure was built. • The structure was subjected to three almost identical soft impact tests. • Response was measured with accelerometers, displacement sensors and strain gauges. • Modal tests was also carried out with the same structure in different conditions. • The results are meant to be used for validation of computational methods and models. - Abstract: Assessing the safety of the reactor building of a nuclear power plant against the crash of an airplane calls for valid computational tools such as finite element models and material constitutive models. Validation of such tools and models in turn calls for reliable and relevant experimental data. The problem is that such data is scarcely available. One of the aspects of such a crash is vibrations that are generated by the impact. These vibrations tend to propagate from the impact point to the internal parts of the building. If strong enough, these vibrations may cause malfunction of the safety-critical equipment inside the building. To enable validation of computational models for this type of behaviour, we have conducted a series of three tests with a wall-floor-wall reinforced concrete structure under soft impact loading. The response of the structure was measured with accelerometers, displacement sensors and strain gauges. In addition to impact tests, the structure was subjected to modal tests under different conditions. The tests yielded a wealth of useful data for validation of computational models and better understanding about shock induced vibration physics especially in reinforced concrete structures.

  5. Review: Impact of underground structures on the flow of urban groundwater

    Science.gov (United States)

    Attard, Guillaume; Winiarski, Thierry; Rossier, Yvan; Eisenlohr, Laurent

    2016-02-01

    Property economics favours the vertical development of cities but flow of groundwater can be affected by the use of underground space in them. This review article presents the state of the art regarding the impact of disturbances caused by underground structures (tunnels, basements of buildings, deep foundations, etc.) on the groundwater flow in urban aquifers. The structures built in the underground levels of urban areas are presented and organised in terms of their impact on flow: obstacle to the flow or disturbance of the groundwater budget of the flow system. These two types of disturbance are described in relation to the structure area and the urban area. The work reviewed shows, on one hand, the individual impacts of different urban underground structures, and on the other, their cumulative impacts on flow, using real case studies. Lastly, the works are placed in perspective regarding the integration of underground structures with the aim of operational management of an urban aquifer. The literature presents deterministic numerical modelling as a tool capable of contributing to this aim, in that it helps to quantify the effect of an underground infrastructure project on groundwater flow, which is crucial for decision-making processes. It can also be an operational decision-aid tool for choosing construction techniques or for formulating strategies to manage the water resource.

  6. Visualizing impact structures using high-resolution LiDAR-derived DEMs: A case study of two structures in Missouri

    Science.gov (United States)

    Finn, Michael P.; Krizanich, Gary W.; Evans, Kevin R.; Cox, Melissa R.; Yamamoto, Kristina H.

    2015-01-01

    Evidence suggests that a crypto-explosive hypothesis and a meteorite impact hypothesis may be partly correct in explaining several anomalous geological features in the middle of the United States. We used a primary geographic information science (GIScience) technique of creating a digital elevation model (DEM) of two of these features that occur in Missouri. The DEMs were derived from airborne light detection and ranging, or LiDAR. Using these DEMs, we characterized the Crooked Creek structure in southern Crawford County and the Weaubleau structure in southeastern St. Clair County, Missouri. The mensuration and study of exposed and buried impact craters implies that the craters may have intrinsic dimensions which could only be produced by collision. The results show elevations varying between 276 and 348 m for Crooked Creek and between 220 and 290 m for Weaubleau structure. These new high- resolution DEMs are accurate enough to allow for precise measurements and better interpretations of geological structures, particularly jointing in the carbonate rocks, and they show greater definition of the central uplift area in the Weaubleau structure than publicly available DEMs.

  7. Weathering of post-impact hydrothermal deposits from the Haughton impact structure: implications for microbial colonization and biosignature preservation.

    Science.gov (United States)

    Izawa, M R M; Banerjee, Neil R; Osinski, G R; Flemming, R L; Parnell, J; Cockell, C S

    2011-01-01

    Meteorite impacts are among the very few processes common to all planetary bodies with solid surfaces. Among the effects of impact on water-bearing targets is the formation of post-impact hydrothermal systems and associated mineral deposits. The Haughton impact structure (Devon Island, Nunavut, Canada, 75.2 °N, 89.5 °W) hosts a variety of hydrothermal mineral deposits that preserve assemblages of primary hydrothermal minerals commonly associated with secondary oxidative/hydrous weathering products. Hydrothermal mineral deposits at Haughton include intra-breccia calcite-marcasite vugs, small intra-breccia calcite or quartz vugs, intra-breccia gypsum megacryst vugs, hydrothermal pipe structures and associated surface "gossans," banded Fe-oxyhydroxide deposits, and calcite and quartz veins and coatings in shattered target rocks. Of particular importance are sulfide-rich deposits and their associated assemblage of weathering products. Hydrothermal mineral assemblages were characterized structurally, texturally, and geochemically with X-ray diffraction, micro X-ray diffraction, optical and electron microscopy, and inductively coupled plasma atomic emission spectroscopy. Primary sulfides (marcasite and pyrite) are commonly associated with alteration minerals, including jarosite (K,Na,H(3)O)Fe(3)(SO(4))(2)(OH)(6), rozenite FeSO(4)·4(H(2)O), copiapite (Fe,Mg)Fe(4)(SO(4))(6)(OH)(2)·20(H(2)O), fibroferrite Fe(SO(4))(OH)·5(H(2)O), melanterite FeSO(4)·7(H(2)O), szomolnokite FeSO(4)·H(2)O, goethite α-FeO(OH), lepidocrocite γ-FeO(OH) and ferrihydrite Fe(2)O(3)·0.5(H(2)O). These alteration assemblages are consistent with geochemical conditions that were locally very different from the predominantly circumneutral, carbonate-buffered environment at Haughton. Mineral assemblages associated with primary hydrothermal activity, and the weathering products of such deposits, provide constraints on possible microbial activity in the post-impact environment. The initial period of

  8. The behavior of osmium and other siderophile elements during impacts: Insights from the Ries impact structure and central European tektites

    Science.gov (United States)

    Ackerman, Lukáš; Magna, Tomáš; Žák, Karel; Skála, Roman; Jonášová, Šárka; Mizera, Jiří; Řanda, Zdeněk

    2017-08-01

    Impact processes are natural phenomena that contribute to a variety of physico-chemical mechanisms over an extreme range of shock pressures and temperatures, otherwise seldomly achieved in the Earth's crust through other processes. Under these extreme conditions with transient temperatures and pressures ≥3000 K and ≥100 GPa, followed by their rapid decrease, the behavior of elements has remained poorly understood. Distal glassy ejecta (tektites) were produced in early phases of contact between the Earth's surface and an impacting body. Here we provide evidence for a complex behavior of Os and other highly siderophile elements (HSE; Ir, Ru, Pt, Pd, and Re) during tektite production related to a hyper-velocity impact that formed the Ries structure in Germany. Instead of simple mixing between the surface materials, which are thought to form the major source of central European tektites (moldavites), and impactor matter, the patterns of HSE contents and 187Re/188Os - 187Os/188Os ratios in moldavites, target sediments and impact-related breccias (suevites) can be explained by several sequential and/or contemporary processes. These involve (i) evaporative loss of partially oxidized HSE from the overheated tektite melt, (ii) mixing of target-derived and impactor-derived HSE vapor (plasma) phases, and (iii) early (high-temperature) condensation of a part of the mixed vapor phase back to silicate melt droplets. An almost complete loss of terrestrial Os from the tektite melt and its replacement with extra-terrestrial Os are indicated by low 187Os/188Os ratios in tektites (0.69). This is paralleled by a co-variation between Os and Ni contents in tektites but not in suevites formed later in the impact process.

  9. The impact of stellar feedback on the density and velocity structure of the interstellar medium

    OpenAIRE

    Grisdale, Kearn; Agertz, Oscar; Romeo, Alessandro B.; Renaud, Florent; Read, Justin I.

    2016-01-01

    We study the impact of stellar feedback in shaping the density and velocity structure of neutral hydrogen (HI) in disc galaxies. For our analysis, we carry out $\\sim 4.6$pc resolution $N$-body+adaptive mesh refinement (AMR) hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way (MW), and a Large and Small Magellanic Cloud (LMC, SMC). We quantify the density and velocity structure of the interstellar medium using power spectra and compare the simulated galaxies to observed ...

  10. Particle-fluid-structure interaction for debris flow impact on flexible barriers

    OpenAIRE

    A. Leonardi; Wittel, F. K.; Mendoza, M.; Vetter, R.; Herrmann, H.J.

    2014-01-01

    Flexible barriers are increasingly used for the protection from debris flow in mountainous terrain due to their low cost and environmental impact. However, a numerical tool for rational design of such structures is still missing. In this work, a hybrid computational framework is presented, using a total Lagrangian formulation of the Finite Element Method (FEM) to represent a flexible barrier. The actions exerted on the structure by a debris flow are obtained from simultaneous simulations of t...

  11. Conserving intertidal habitats: What is the potential of ecological engineering to mitigate impacts of coastal structures?

    Science.gov (United States)

    Perkins, Matthew J.; Ng, Terence P. T.; Dudgeon, David; Bonebrake, Timothy C.; Leung, Kenneth M. Y.

    2015-12-01

    Globally, coastlines are under pressure as coastal human population growth and urbanization continues, while climatic change leads to stormier seas and rising tides. These trends create a strong and sustained demand for land reclamation and infrastructure protection in coastal areas, requiring engineered coastal defence structures such as sea walls. Here, we review the nature of ecological impacts of coastal structures on intertidal ecosystems, seek to understand the extent to which ecological engineering can mitigate these impacts, and evaluate the effectiveness of mitigation as a tool to contribute to conservation of intertidal habitats. By so doing, we identify critical knowledge gaps to inform future research. Coastal structures alter important physical, chemical and biological processes of intertidal habitats, and strongly impact community structure, inter-habitat linkages and ecosystem services while also driving habitat loss. Such impacts occur diffusely across localised sites but scale to significant regional and global levels. Recent advances in ecological engineering have focused on developing habitat complexity on coastal structures to increase biodiversity. 'Soft' engineering options maximise habitat complexity through inclusion of natural materials, species and processes, while simultaneously delivering engineering objectives such as coastal protection. Soft options additionally sustain multiple services, providing greater economic benefits for society, and resilience to climatic change. Currently however, a lack of inclusion and economic undervaluation of intertidal ecosystem services may undermine best practice in coastline management. Importantly, reviewed evidence shows mitigation and even restoration do not support intertidal communities or processes equivalent to pre-disturbance conditions. Crucially, an absence of comprehensive empirical baseline biodiversity data, or data comprising additional ecological parameters such as ecosystem functions

  12. The Edgerton Structure: A Possible Meteorite Impact Feature in Eastern Kansas

    Directory of Open Access Journals (Sweden)

    Daniel F. Merriam

    2009-01-01

    Full Text Available Recognized meteorite impact features are relatively rare in the U.S. Midcontinent region, but recently with increased interest and research, the number has increased dramatically. We add another possibility to the growing list, the Edgerton structure in northwestern Miami County, Kansas. The feature is elliptical (∼5.5 × 6.5 km, slightly elongated east-west with radial surface drainage. The feature was first observed on hillshade maps of digitized topography of 7.5 minute quadrangles. Subsequent magnetic profiles show a higher magnetic value in the center of the ellipse with higher values around the edges; this shape is characteristic of an impact feature. Depth to the anomalous body is estimated to be about 1 km, which puts it in the Precambrian crystalline basement under a cover of Paleozoic sediments. There are no deep boreholes in the vicinity and no seismic profiles are available. If it is an impact structure, it will be the second such feature documented in Kansas, the first being the Brenham meteorite crater at Haviland in Kiowa County in southwestern Kansas. It would be older than the other impact structures identified in the Midcontinent—Manson in Iowa, Ames in Oklahoma, Haswell Hole in Colorado, and possibly Belton in Missouri and Merna in Nebraska. There are at least two other prospective impact features in Kansas: the Goddard ring west of Wichita and Garden City ellipse north-west of Garden City.

  13. Numerical modeling of the formation and structure of the Orientale impact basin

    Science.gov (United States)

    Potter, Ross W. K.; Kring, David A.; Collins, Gareth S.; Kiefer, Walter S.; McGovern, Patrick J.

    2013-05-01

    The Orientale impact basin is the youngest and best-preserved lunar multi-ring basin and has, thus, been the focus of studies investigating basin-forming processes and final structures. A consensus about how multi-ring basins form, however, remains elusive. Here we numerically model the Orientale basin-forming impact with the aim of resolving some of the uncertainties associated with this basin. By using two thermal profiles estimating lunar conditions at the time of Orientale's formation and constraining the numerical models with crustal structures inferred from gravity data, we provide estimates for Orientale's impact energy (2-9 × 1025 J), impactor size (50-80 km diameter), transient crater size (˜320-480 km), excavation depth (40-55 km), and impact melt volume (˜106 km3). We also analyze the distribution and deformation of target material and compare our model results and Orientale observations with the Chicxulub crater to investigate similarities between these two impact structures.

  14. Measurement of deforming mode of lattice truss structures under impact loading

    Directory of Open Access Journals (Sweden)

    Zhao H.

    2012-08-01

    Full Text Available Lattice truss structures, which are used as a core material in sandwich panels, were widely investigated experimentally and theoretically. However, explanation of the deforming mechanism using reliable experimental results is almost rarely reported, particularly for the dynamic deforming mechanism. The present work aimed at the measurement of the deforming mode of lattice truss structures. Indeed, quasi-static and Split Hopkinson Pressure Bar (SHPB tests have been performed on the tetrahedral truss cores structures made of Aluminum 3003-O. Global values such as crushing forces and displacements between the loading platens are obtained. However, in order to understand the deforming mechanism and to explain the observed impact strength enhancement observed in the experiments, images of the truss core element during the tests are recorded. A method based on the edge detection algorithm is developed and applied to these images. The deforming profiles of one beam are extracted and it allows for calculating the length of beam. It is found that these lengths diminish to a critical value (due to compression and remain constant afterwards (because of significant bending. The comparison between quasi-static and impact tests shows that the beam were much more compressed under impact loading, which could be understood as the lateral inertia effect in dynamic bucking. Therefore, the impact strength enhancement of tetrahedral truss core sandwich panel can be explained by the delayed buckling of beam under impact (more compression reached, together with the strain hardening of base material.

  15. Formation of a small impact structure discovered within the Agoudal meteorite strewn field, Morocco

    Science.gov (United States)

    Lorenz, C. A.; Ivanova, M. A.; Artemieva, N. A.; Sadilenko, D. A.; Chennaoui Aoudjehane, H.; Roschina, I. A.; Korochantsev, A. V.; Humayun, M.

    2015-01-01

    A relic impact structure was recognized within the strewn field of the Agoudal iron meteorite. The heavily eroded structure has preserved shatter cones in a limestone basement, and remnants of autochthonous and allochthonous breccias. Fragments of iron incorporated into the allochthonous breccia have a chemical composition (Ni = 5.16 wt%, Ir = 0.019 ppm) similar to that of the Agoudal meteorite, supporting a syngenetic origin of the strewn field and the impact structure. The total recovered mass of Agoudal meteorite fragments is estimated at approximately 500 kg. The estimated size of the SE-NW-oriented strewn field is 6 × 2 km. Model calculations with minimal preatmospheric size show that a similar meteorite strewn field plus one small crater with observed shock effects could be formed by fragmentation of a meteoroid approximately 1.4 m in diameter with an impact angle of approximately 60° from the horizontal. However, the most probable is an impact of a larger, 3-4 m diameter meteoroid, resulting a strewn field with approximately 10 craters, 10-30 m in diameter each, plus numerous meteorite fragments. The calculated scattering area of meteorite shrapnel ejected from these impact craters could completely cover the observed strewn field of the Agoudal meteorite.

  16. Impact Resistance of Lightweight Hybrid Structures for Gas Turbine Engine Fan Containment Applications

    Science.gov (United States)

    Hebsur, Mohan G.; Noebe, Ronald D.; Revilock, Duane M.

    2003-01-01

    The ballistic impact resistance of hybrid composite sandwich structures was evaluated with the ultimate goal of developing new materials or structures for potential gas turbine engine fan containment applications. The sandwich structures investigated consisted of GLARE-5 laminates as face sheets with lightweight cellular metallic materials such as honeycomb, foam, and lattice block as a core material. The impact resistance of these hybrid sandwich structures was compared to GLARE-5 laminates and 2024-T3 Al sheet, which were tested as a function of areal weight (material thickness). The GLARE-5 laminates exhibited comparable impact properties to that of 2024-T3 Al at low areal weights, even though there were significant differences in the static tensile properties of these materials. The GLARE-5, however, did have a greater ballistic limit than straight aluminum sheet at higher areal weights. Furthermore, there is up to a 25% advantage in ballistic limit for the GLARE-5/foam sandwich structures compared to straight 2024-T3 Al. But no advantage in ballistic limit was observed between any of the hybrid sandwich structures and thicker versions of GLARE-5. Recommendations for future work are provided, based on these preliminary data.

  17. Bird impact at aircraft structure - Damage analysis using Coupled Euler Lagrangian Approach

    Science.gov (United States)

    Smojver, I.; Ivancevic, D.

    2010-06-01

    Numerical bird strike damage prediction procedure has been applied on the very detailed large airplane secondary structure consisting of sandwich, composite and metallic structural items. The impacted inboard flap finite element model is modelled using 3D, shell and continuum shell elements, coupled with appropriate kinematic constraints. The bird has been modelled using Coupled Euler Lagrangian approach, in order to avoid the numerical difficulties connected with mesh distortion. Various failure modes, such as Carbon Fibre Reinforced Plastics (CFRP) face layer rupture, failure of composite matrix, damage initiation / evolution in the sandwich structure Nomex core and elastoplastic failure of a metallic structure have been investigated. Besides, general contact has been applied as to efficiently capture the contact between Eulerian bird material and the structure, as well as large deformations of the different structural components. Compared to the classic Lagrangian modelling of the bird, the analysis has proven to be more stable, and the results, such as damage areas, physically more realistic. The impact has been applied in the area that is the most probably subjected to the impact damage during exploitation.

  18. Study on the Analytical Behaviour of Concrete Structure Against Local Impact of Hard Missile

    Directory of Open Access Journals (Sweden)

    Ahmad Mujahid Ahmad Zaidi

    2011-07-01

    Full Text Available Concrete is basic construction material used for almost all kind of structure. However, in the majority essential structures such as nuclear plants, Power plants, Weapon Industries, weapons storage places, water retaining structures like dams, highways barriers, bridges, & etc., concrete structures have to be designed as self-protective structure which can afford any disaster or consciously engendered unpleasant incidents such as incident occurs in nuclear plants, incident in any essential industry, terrorist attack, Natural disasters like tsunami and etc missile attack, and local impact damage generated by kinetic missiles dynamic loading (steel rods, steel pipes, turbine blades, etc.. This paper inquisitively is paying attention on verdict of the recent development in formulating analytical behavior of concrete and reinforced concrete structures against local impact effect generated by hard missile with and without the influence of dimensional analysis based on dominant non-dimensional parameters, various nose shape factors at normal and certain inclined oblique angles. The paper comprises the analytical models and methods for predicting penetration, and perforation of concrete and reinforced concrete. The fallout conquer from this study can be used for making design counsel and design procedures for seminal the dynamic retort of the concrete targets to foil local impact damage.

  19. The Skin Picking Impact Scale: Factor structure, validity and development of a short version.

    Science.gov (United States)

    Snorrason, Ivar; Olafsson, Ragnar P; Flessner, Christopher A; Keuthen, Nancy J; Franklin, Martin E; Woods, Douglas W

    2013-08-01

    In the present study, we examined the psychometric properties of the Skin Picking Impact Scale (SPIS; Keuthen, Deckersbach, Wilhelm et al., 2001), a 10 item self-report questionnaire designed to assess the psychosocial impact of skin picking disorder (SPD). Participants were 650 individuals who met criteria for SPD in an online survey. Exploratory and confirmatory factor analyses demonstrated a unitary factor structure with high internal consistency (α = 0.94). Consequently, we constructed an abbreviated 4-item version that retained good internal consistency (α = 0.87) and a robust factor structure. Both the short and the full versions demonstrated discriminant and convergent/concurrent validity. In conclusion, the findings indicate that both versions are psychometrically sound measures of SPD related psychosocial impact; however, some potential limitations of the full scale are discussed.

  20. Experimental study of wave impact on the nearshore structures during extreme coastal floods

    Science.gov (United States)

    Sriram, Venkatachalam; Didenkulova, Ira; Pelinovsky, Efim; Rodin, Artem; Didenkulov, Oleg; Sergeeva, Anna; Nair Vishnu, Reghunathan; Sundar, Vallam; Annamalaisamy Sannasiraj, Sannasi

    2016-04-01

    We study the dynamics of strongly nonlinear waves in the coastal zone and their impact on coasts during flash floods and tsunami. For this we use analytical theory of strongly nonlinear wave propagation along the slope and compare it with the data of experiments carried out in shallow water flume of IIT Madras (72 m long, 2 m wide and up to 2 m deep). Different kinds of waves like elongated solitons, N-waves are simulated and its run-up and impact force on the idealized structure on the slope are evaluated. Different numerical models (CLAWPACK, pseudospectral code for solving nonlinear evolutional equations and FNPT model) areused to describe strongly nonlinear waves along the slope. Results of numerical simulations are compared with predictions of analytical theory and with the data of experiments. The results presented here are the preliminary results obtained within DST - RFBR joint project "Impact of waterborne debris on the nearshore structures during extreme coastal floods".

  1. Impacts of feeding strategy on microbial community structure diversity in vertical flow constructed wetlands

    Science.gov (United States)

    Jia, W. L.; Zhang, J.; Wang, Q.

    2016-08-01

    The impacts of feeding strategy (intermittently or continuously) on contaminant removal performance and microbial community structure in vertical flow constructed wetlands (VFCWs) were evaluated. The results showed that intermittent feeding strategy improved the removal of COD, TP and ammonium in VFCWs, although TN removal was weakened correspondingly The bacterial diversity decreased with the increase of substratum depth in all CWs. The intermittent feeding favored the growth of microorganisms due to the enhancement of oxygen content in the substratum. The feeding strategy had little impact on the microbial community in the surface substratum. However, in the bottom substratum, the impacts were of great significance. The microbial community structure similarity between the CWs with different feeding strategies was low.

  2. Elements of the Chicxulub Impact Structure as Revealed in SRTM and Surface GPS Topographic Data

    Science.gov (United States)

    Kinsland, Gary L.; Sanchez, Gary; Kobrick, Michael; Cardador, Manuel Hurtado

    2003-01-01

    Pope et al. [1] utilized the elevations from the Petroleos Mexicanos (PEMEX) gravity data files to show that the main component of the surface expression of the Chicxulub Impact Structure is a roughly semi-circular, lowrelief depression about 90 km in diameter. They also identified other topographic features and the elements of the buried impact, which possibly led to the development of these features. These are summarized in Table 1. Kinsland et al. [2] presented a connection between these topographic anomalies, small gravity anomalies and buried structure of the impact. Very recently we have acquired digital topography data from NASA s Shuttle Radar Topography Mission (SRTM). Our subset covers 6 square degrees from 20deg N 91degW to 22deg N 88degW (corner to corner) with a pixel size of about 90m. This area includes all of the identified portion of the crater on land.

  3. U/Pb Dating of Zircon from the Suvasvesi Impact Structures, Finland

    Science.gov (United States)

    Schwarz, W. H.; Breutmann, G.; Schmitt, A. K.; Trieloff, M.; Ludwig, T.; Hanel, M.; Buchner, E.; Schmieder, M.; Pesonen, L. J.; Moilanen, J.

    2016-08-01

    The two Suvasvesi impact structures (Finland), both covered by lakes, forming an apparent crater doublet, were analysed by in-situ U/Pb dating of zircon grains, concluding that the two craters were formed in separate events, ~600 Ma apart.

  4. Characterization and morphological reconstruction of the Terny impact structure, central Ukraine

    Science.gov (United States)

    Sharpton, V. L.; Krochuk, R. V.; Herrick, R. R.

    2013-05-01

    The Terny impact structure, located in central Ukraine, displays a variety of diagnostic indicators of shock metamorphism, including shatter cones, planar deformation features in quartz, diaplectic glass, selective melting of minerals, and whole rock melting. The structure has been modified by erosion and subsequently buried by recent sediments. Although there are no natural outcrops of the deformed basement rocks within the area, mining exploration has provided surface and subsurface access to the structure, exposing impact melt rocks, shocked parautochthonous target rocks, and allochthonous impact breccias, including impact melt-bearing breccias similar to suevites observed at the Ries structure. We have collected and studied samples from surface and subsurface exposures to a depth of approximately 750 m below the surface. This analysis indicates the Terny crater is centered on geographic coordinates 48.13° N, 33.52° E. The center location and the distribution of shock pressures constrain the transient crater diameter to be no less than approximately 8.4 km. Using widely accepted morphometric scaling relations, we estimate the pre-erosional rim diameter of Terny crater to be approximately 16-19 km, making it close in original size to the well-preserved El'gygytgyn crater in Siberia. Comparison with El'gygytgyn yields useful insights into the original morphology of the Terny crater and indicates that the amount of erosion Terny experienced prior to burial probably does not exceed 320 m.

  5. The Structure at Sierra Ambato, Catamarca, Argentina: A New Meteorite Impact Site?

    Science.gov (United States)

    Acevedo, R. D.; Rocca, M.; Alonso, R.; Rabassa, J.; Ponce, J. F.

    2012-09-01

    A new possible impact crater was discovered in Catamarca Province: the structure at Sierra Ambato (28º 03" 23.22” S, 66º 03" 11.06” W), located at Sierras Pampeanas (3,500 m.a.s.l). It has 1.0 km in diameter.

  6. The impact of powder diffraction on the structural characterization of organic crystalline materials.

    Science.gov (United States)

    Tremayne, Maryjane

    2004-12-15

    The bulk properties of organic crystalline materials depend on their molecular and crystal structures but, as many of these materials cannot be prepared in a suitable form for conventional single-crystal diffraction studies, structural characterization and rationalization of these properties must be obtained from powder diffraction data. The recent development of direct-space structure solution methods has enabled the study of a wide range of organic materials using powder diffraction data, many of structural complexity only made tractable by these advances in methodology. These direct-space methods are based on a number of global optimization techniques including Monte Carlo, simulated annealing, genetic algorithm and differential evolution approaches. In this article, the implementation and relative efficiency and reliability of these methods are discussed, and their impact on the structural study of organic materials is illustrated by examples of polymorphic systems, pharmaceutical, pigment and polypeptide structures and compounds used in the study of intermolecular networks.

  7. Deterministic modeling of the impact of underground structures on urban groundwater temperature.

    Science.gov (United States)

    Attard, Guillaume; Rossier, Yvan; Winiarski, Thierry; Eisenlohr, Laurent

    2016-12-01

    Underground structures have a major influence on groundwater temperature and have a major contribution on the anthropogenic heat fluxes into urban aquifers. Groundwater temperature is crucial for resource management as it can provide operational sustainability indicators for groundwater quality and geothermal energy. Here, a three dimensional heat transport modeling approach was conducted to quantify the thermally affected zone (TAZ, i.e. increase in temperature of more than +0.5°C) caused by two common underground structures: (1) an impervious structure and (2) a draining structure. These design techniques consist in (1) ballasting the underground structure in order to resist hydrostatic pressure, or (2) draining the groundwater under the structure in order to remove the hydrostatic pressure. The volume of the TAZ caused by these underground structures was shown to range from 14 to 20 times the volume of the underground structure. Additionally, the cumulative impact of underground structures was assessed under average thermal conditions at the scale of the greater Lyon area (France). The heat island effect caused by underground structures was highlighted in the business center of the city. Increase in temperature of more than +4.5°C were locally put in evidence. The annual heat flow from underground structures to the urban aquifer was computed deterministically and represents 4.5GW·h. Considering these impacts, the TAZ of deep underground structures should be taken into account in the geothermal potential mapping. Finally, the amount of heat energy provided should be used as an indicator of heating potential in these areas.

  8. The thermal impact of subsurface building structures on urban groundwater resources - A paradigmatic example.

    Science.gov (United States)

    Epting, Jannis; Scheidler, Stefan; Affolter, Annette; Borer, Paul; Mueller, Matthias H; Egli, Lukas; García-Gil, Alejandro; Huggenberger, Peter

    2017-10-15

    Shallow subsurface thermal regimes in urban areas are increasingly impacted by anthropogenic activities, which include infrastructure development like underground traffic lines as well as industrial and residential subsurface buildings. In combination with the progressive use of shallow geothermal energy systems, this results in the so-called subsurface urban heat island effect. This article emphasizes the importance of considering the thermal impact of subsurface structures, which commonly is underestimated due to missing information and of reliable subsurface temperature data. Based on synthetic heat-transport models different settings of the urban environment were investigated, including: (1) hydraulic gradients and conductivities, which result in different groundwater flow velocities; (2) aquifer properties like groundwater thickness to aquitard and depth to water table; and (3) constructional features, such as building depths and thermal properties of building structures. Our results demonstrate that with rising groundwater flow velocities, the heat-load from building structures increase, whereas down-gradient groundwater temperatures decrease. Thermal impacts on subsurface resources therefore have to be related to the permeability of aquifers and hydraulic boundary conditions. In regard to the urban settings of Basel, Switzerland, flow velocities of around 1 md(-1) delineate a marker where either down-gradient temperature deviations or heat-loads into the subsurface are more relevant. Furthermore, no direct thermal influence on groundwater resources should be expected for aquifers with groundwater thicknesses larger 10m and when the distance of the building structure to the groundwater table is higher than around 10m. We demonstrate that measuring temperature changes down-gradient of subsurface structures is insufficient overall to assess thermal impacts, particularly in urban areas. Moreover, in areas which are densely urbanized, and where groundwater flow

  9. Contribution to the modelling and simulation of aircraft structures impacting on water

    OpenAIRE

    Toso, Nathalie Renée Solange

    2009-01-01

    The impact on water of aeronautical structures is of concern as soon as an aircraft is designed to operate over sea. For the need of the ditching certification, it can be summarised that the structure should be able to land on water and float long enough to enable the passengers and crew members to evacuate. Until the middle of the 90's, compliance to the regulations was mainly shown by tests performed in a basin using a mock-up structure completed by relative simple theoretical evaluations o...

  10. Structural Changes of International Trade Flows under the Impact of Globalization

    Directory of Open Access Journals (Sweden)

    Anca Dachin

    2006-08-01

    Full Text Available Structural changes of international trade flows indicate modifications in competitiveness of countries, in terms of production, technological upgrading and exports under the pressure of globalization. The paper aims to point out sources of competitive advantages especially in manufacturing exports of different groups of countries. The focus is on the shifts in the structure of manufacturing in the European Union and their effects on international rankings in export performances. An important issue refers to the opportunities given by the enlargement of the European Union and their impact on EU trade structures.

  11. Analysis on Impact Factors of Water Utilization Structure in Tianjin, China

    Directory of Open Access Journals (Sweden)

    Conglin Zhang

    2016-03-01

    Full Text Available Water is an essential foundation for socio-economic development and environmental protection. As such, it is very critical for a city’s sustainable development. This study analyzed the changes in water utilization structure and its impact factors using water consumption data for agricultural, industrial, domestic and ecological areas in the city of Tianjin, China from 2004 to 2013. On this base, the evolution law and impact factors of water utilization structure were depicted by information entropy and grey correlation respectively. These analyses lead to three main results. First, the total amount of water consumption in Tianjin increased slightly from 2004 to 2013. Second, the information entropy and equilibrium degree peaked in 2010. From 2004 to 2010, the water utilization structure tended to be more disordered and balanced. Third, the economic and social factors seemed to influence the water utilization structure, while the main impact factors were industrial structure, per capita green area, cultivated area, effective irrigation area, rural electricity consumption, animal husbandry output, resident population, per capita domestic water etc.

  12. The impact of ligands on the structure and flexibility of sulfotransferases: a molecular dynamics simulation study.

    Science.gov (United States)

    Zhao, Li; Zhang, Pupu; Long, Shiyang; Wang, Linlin; Tian, Pu

    2015-08-01

    Sulfotransferases catalyze transfer of the sulfuryl-group (-SO3) from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to a large number of substrates. They play an important role in phase II metabolic process. The impact of the cofactor (PAPS) on the structure and flexibility of the enzyme has been studied extensively, and the response of the active-cap region to cofactor binding was proposed as the molecular basis for substrate selectivity. In this study, individual and cooperative effects of the cofactor and substrate on the structure and flexibility of the enzyme were investigated. Molecular dynamics simulations were performed for four systems, including free enzyme, binary complexes (cofactor or substrate bound enzyme) and ternary complex (both cofactor and substrate bound enzyme). The influence of ligands (the cofactor and the substrate) on the structure and flexibility of the enzyme, especially that of the active-site cap region, was analyzed. Moreover, mutual structural impact of the ligands was examined as well. The results show that the impact of both the cofactor and the substrate was significant. Our study indicated that the substrate, such as lithocholic acid (LCA), participated in regulating the structure and flexibility of the enzyme actively rather than merely being selected passively. Additionally, the observed synergistic effects of the cofactor and the substrate demonstrated the importance of examining both ligands in understanding enzymes.

  13. Crushable Structure for the Landing Impact of a European Mars Exploration Mission (ExoMars 2016)

    Science.gov (United States)

    del Campo, F.; Bernar, E.; Biondetti, G.; Jauregui, Y. E.; Walloschek, T.

    2012-07-01

    The first mission of the ExoMars programme, scheduled to arrive at Mars in 2016, includes an Entry, Descent and Landing Demonstrator Module (EDM). One of the EDM objectives is to demonstrate the possibility to safely absorb the landing impact by means of a deformable structure placed under the Surface Platform (SP), the EDM sub-module reaching ground. This is one of the key technologies in preparation for ESA's contribution to subsequent missions to Mars. SENER is responsible for several structures and mechanisms for the EDM, with TAS-I as Prime contractor. The paper focuses on the Crushable Structure, which is the main element affected by the impact. Its function is to absorb the landing impact after thruster switch off at around 2 meters over the Martian surface, allowing a safe landing for the equipments in terms of acceleration levels, and for the whole structure in terms of stability and non-overturning. An optimized structure has been designed for this purpose, within a restricted envelope, able to meet these requirements for a wide range of terrain configurations, including rocks and slopes.

  14. Chicxulub impact basin: Gravity characteristics and implications for basin morphology and deep structure

    Science.gov (United States)

    Sharpton, Virgil L.; Burke, Kevin; Hall, Stuart A.; Lee, Scott; Marin, Luis E.; Suarez, Gerardo; Quezada-Muneton, Juan Manuel; Urrutia-Fucugauchi, Jaime

    1993-01-01

    The K-T-aged Chicxulub Impact Structure is buried beneath the Tertiary carbonate rocks of the Northern Yucatan Platform. Consequently its morphology and structure are poorly understood. Reprocessed Bouguer (onshore) and Free Air (offshore) gravity data over Northern Yucatan reveal that Chicxulub may be a 200-km-diameter multi-ring impact basin with at least three concentric basin rings. The positions of these rings follow the square root of 2 spacing rule derived empirically from analysis of multi-ring basins on other planets indicating that these rings probably correspond to now-buried topographic basin rings. A forward model of the gravity data along a radial transect from the southwest margin of the structure indicates that the Chicxulub gravity signature is compatible with this interpretation. We estimate the basin rim diameter to be 204 +/- 16 km and the central peak ring diameter (D) is 104 +/- 6 km.

  15. Adopting Continuous Delivery and Deployment: Impacts on Team Structures, Collaboration and Responsibilities

    DEFF Research Database (Denmark)

    Shahin, Mojtaba; Zahedi, Mansooreh; Babar, Muhammad Ali

    2017-01-01

    Context: Continuous Delivery and Deployment (CD) practices aim to deliver software features more frequently and reliably. While some efforts have been made to study different aspects of CD practices, a little empirical work has been reported on the impact of CD on team structures, collaboration...... and team members’ responsibilities. Goal: Our goal is to empirically investigate how Development (Dev) and Operations (Ops) teams are organized in software industry for adopting CD practices. Furthermore, we explore the potential impact of practicing CD on collaboration and team members’ responsibilities....... Method: We conducted a mixed-method empirical study, which collected data from 21 in- depth, semi-structured interviews in 19 organizations and a survey with 93 software practitioners. Results: There are four common types of team structures (i.e., (1) separate Dev and Ops teams with higher collaboration...

  16. Geophysical characterization of circular structures in Chubut and Mendoza (Argentina): Impact vs. Volcanism

    Science.gov (United States)

    Prezzi, C.; Orgeira, M. J.; Risso, C.; Acevedo, R.; Ponce, F.; Nullo, F.; Martinez, O.; Rabassa, J.; Margonari, L.; Corbella, H.

    2013-05-01

    This work focuses on two main objectives. One of them is to provide information to discern the genesis of the circular structures present in Bajada del Diablo (Chubut, Argentina) considered as impact craters, and the other one is to contribute to a better knowledge of the circular structures located in the volcanic fields of Llancanelo and Payunia (Mendoza, Argentina). Chubut circular structures have been attributed to the collision of an extraterrestrial body, possibly an asteroid. However, doubts persist about their genesis because of the lack of direct geological evidences. Since detailed geomorphological studies have ruled out an origin by wind deflation, the prevailing alternative hypothesis attributes these circular structures to a volcanic process. On the other hand, the study of the volcanic fields of Payunia and Llancanelo (Mendoza) will contribute to the knowledge of the mechanics of hydromagmatic processes in the area, and the origin of circular structures morphologically similar to those located in Chubut. In the Payunia volcanic field at least 27 cones with evidences of hydromagmatism, in a field of more than 800 pure magmatic cones, have been recognized. This study tries to determine if a relationship between the observed volcanic circular structures and participation of water during the eruption exists. Magnetic and gravity field surveys of the circular volcanic structures in Llancanelo and Payunia volcanic fields were performed in order to determine their relationship with the type of eruption. Electromagnetic, magnetic and gravity field surveys were also carried out in Chubut circular structures. The comparative analysis of geological and geophysical results obtained in the circular structures of Chubut and those obtained in the circular structures in the volcanic areas of Llancanelo and Payunia suggest an impact origin for the circular structures of Chubut.

  17. The mediterranean coast of Andalusia (sw spain): the impacts of human coastal structures

    Science.gov (United States)

    Liguori, Vincenzo; Manno, Giorgio; Messina, Enrica; Anfuso, Giorgio; Suffo, Miguel

    2015-04-01

    Spanish coasts, especially the Andalusia Mediterranean one, were affected over time by progressive urbanization and associated construction of defense structures. Such structures protected small coastal sectors but at places triggered processes of coastal erosion and associated degradation of habitats and ecosystems. A correct management of coastal areas must be based on the monitoring of coastal evolution and human pressure. A useful tool to evaluate the level of human anthropization is the estimation of the "Coastal Armouring", e.g. the quantification of coastal defense structures, infrastructures, ports, etc. In this study, available aerial photographs and satellite images from 1956 to 2011 were scanned and geo-referenced and used for the quantitative assessment of coastal human constructions impact on the studied coastal area. The so called coefficient of technogenous impact (K) was used. It results from the relationship between the total length of all maritime structures (groins, moles, seawalls, dikes, channels, etc.) and the entire length of the study coastal section. For this purpose, the Andalusia coast, about 500 km in length, was divided into sections of 1 km. For each one of such sections the technogenous impact was calculated in the 1956 and 2011 documents. The analysis showed that the degree of anthropization in some areas (for example the Port of Montril) has increased considerably, triggering degradation processes in the nearby coastal areas. Results also evidenced as, in many cases, greatest human impacts are linked to the progressive construction of coastal defense. The lack of a general strategy to combat the erosion problem and the urgency in the short term to protect specific parts of the coast led to a reactive approach based initially in the construction of hard structures. Such interventions locally solved erosion problems but gave rise to drowndrift erosion according to the "domino" effect. A more general management plan is needed

  18. Pronounced central uplift identified in the Bosumtwi impact structure, Ghana, using multichannel seismic reflection data

    Science.gov (United States)

    Scholz, Christopher A.; Karp, Tobias; Brooks, Keely M.; Milkereit, Bernd; Amoako, Philip Y. O.; Arko, Justice A.

    2002-10-01

    The Lake Bosumtwi impact structure is the youngest and best-preserved complex terrestrial impact crater and serves as an important reference site for the study of cratering processes. Because the impacting body struck continental crystalline target rocks and not a submerged sedimentary platform, no significant backwash processes have modified the crater morphology. Not only may Bosumtwi contain the best-preserved central uplift structure on Earth, but it is the most accessible relatively large, young crater in the solar system generated in a large gravity field. There is a well-established link between the Lake Bosumtwi impact structure and the Ivory Coast tektite field, and the lacustrine sediments within the crater contain a unique 1 m.y. record of paleoclimate in the continental tropics south of the Sahel. Eight profiles of marine-type multichannel seismic reflection (MCS) data were acquired from the 8-km-diameter, ˜75-m-deep lake that fills much of the crater. These were augmented by wide-angle seismic data acquired with ocean-bottom hydrophones. MCS data reveal a well-defined central uplift near the northwest-central part of the lake and a maximum postimpact lacustrine sediment thickness of ˜310 m. The central uplift structure has a diameter of 1.9 km and a maximum height of 130 m above the annular moat inside the crater. An intermediate velocity layer (3200 m/s) beneath the lacustrine sediment is interpreted as fallback breccia or a breccia-melt horizon. The measured apparent depth of the crater (da) is 500 m, implying a slightly higher aspect ratio for the structure than predicted from published empirical relationships. The Bosumtwi structure is a small complex crater that deviates slightly from trends predicted from classical scaling laws, perhaps because of the effects of a large gravity field.

  19. Evaluation of the Impact of the EU Structural Support on the Competitiveness of Lithuanian Economics

    Directory of Open Access Journals (Sweden)

    Remeikiene Rita

    2016-05-01

    Full Text Available The topic of competitiveness is becoming increasingly significant in the context of modern economics. Considering intensive processes of globalisation alongside with competitive pressure amongst the countries, competitiveness has become a necessary condition for successful economic and social development of any country. Only by creating, enforcing and maintaining international competitiveness of the country, rapid economic growth during the long term is achievable. Amongst the other urgent issues, the European Union (further the EU public policies are also focused on competitiveness. After the failure to implement the Lisbon strategy and become “the most dynamic and competitive knowledge-based economy”, the EU declared its new competitiveness aims in the long-term strategy Europe 2020. Promotion of competitiveness is one of the fundamental aims and priority directions of the EU structural policy. The EU structural support is engaged as one of the public policy measures to promote the competitiveness of the member-states. In this context, it is purposeful to research whether the structural support is used efficiently and whether it actually contributes to the implementation of the defined aims. Under the order of various Lithuanian institutions, numerous studies on the efficiency of the EU structural support have been carried out. Nevertheless, by analysing the impact of the EU structural support, insufficient attention has been paid to the aspect of competitiveness. Considering the fact that Lithuania has entered the third programming period 2014-2020, evaluation of the EU structural investment in the country has become even more topical - for successful implementation of the aims raised for this new period, the analysis of the previous results is relevant. This determined formulation of the research problem: what impact does the EU structural support have on the competitiveness of Lithuanian economics? The empirical research has revealed

  20. Evidence for a Putative Impact Structure in Palm Valley, Central Australia

    Science.gov (United States)

    Hamacher, D. W.; O'Neill, C.; Buchel, A.; Britton, T. R.

    2010-07-01

    Introduction: We present evidence supporting the impact origin of a circular structure located in Palm Valley, Central Australia (24° 03' 06'' S, 132° 42' 34'' E). The ~280 m wide structure was discovered using a combination of Google Maps and a local Arrernte Aboriginal oral tradition regarding a star that fell into a waterhole called Puka in Palm Valley, Northern Territory [1][2] (see [3] for details of the discovery). Geophysical Evidence: A survey of the structure in September 2009 collected magnetic, gravity and topographic data. Geophysical modeling of the data revealed the structure has a bowl-shaped subsurface morphology, as expected for a simple impact crater. Though the structure sits within the Finke Gorge system, the models do not support an erosional origin for the structure, as no buried channels are observed. Nor does the modeling fit a volcanic origin, as the density structure at depth is consistent with fractured sandstone/sediments. Geological Evidence: One channel runs out of the crater to the south, consistent with outflow from crater-filling events, but again not with an erosional origin for the structure itself. The microstructure of rock samples collected from the site revealed the presence of planar deformation features in the quartz grains. The coincident angle of the fractures is consistent with the crystallographic fracture directions under mild-end shocks. These grains probably represent local focusing of stress as the shock wave moved through the heterogeneous grain matrix, suggesting the conditions were right for the shock pressure to locally exceed the ~7.5 GPa required to form the features, even though the bulk of the shock pressure was much less. Conclusion: Based on the level of erosion and the absence of shatter cones and meteorite fragments, we estimate the structure's age to be in the millions of years. While the presence of shocked-quartz is a direct indicator of a cosmic impact, we cannot rule out that the quartz was

  1. Osmium-isotope Evidence for a Projectile Component in Impact-melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA

    Science.gov (United States)

    Lee, S.; Horton, J. W.; Walker, R. J.

    2004-12-01

    The late Eocene Chesapeake Bay impact structure (CBIS) is preserved beneath post-impact sediments on the Atlantic margin of Virginia. This 85-km-diameter complex crater formed on the continental shelf of a passive margin in a layered target consisting of ocean water, Cretaceous and Tertiary sediments (mainly siliciclastic), and crystalline basement rocks. The basement rocks include Neoproterozoic granitoids and felsite as well as gneiss of undetermined age. In May, 2004, the USGS drilled an 823-m test hole in the central uplift of the CBIS at Cape Charles, Va., providing drill cuttings and limited core. The core from 744 to 823 m depth contains crystalline-clast breccia and brecciated gneiss that are distinct from sediment-clast breccias recovered from coreholes in the annular trough of the CBIS. Rocks interpreted to be impact-melt clasts and dikes in the crystalline-clast breccia were sampled for analyses of osmium (Os) concentrations and 187Os/188Os ratios to test for evidence of the projectile. These analyses were conducted on samples from a dike (aphanitic to partly hyaline, ST2440.8C) within a gneissic block, from a block of holocrystalline mafic rock (aphanitic, ST2453.3C), and from a flow-laminated bomb (aphanitic to partly hyaline, ST2570.0C). The Os concentrations and 187Os/188Os ratios for samples ST2440.8C, ST2453.3C and ST2570.0C are 0.928, 0.711 and 0.312 ppb, and 0.15205, 0.15545 and 0.22345, respectively. These values are much higher (Os) or lower (187Os/188Os) than those reported for rocks of the upper continental crust, suggesting a significant contribution of osmium from the projectile in these impact-melt rocks. Moreover, a strong negative correlation between 187Os/188Os and Os for these samples suggests that it may be possible to use mixing curves to calculate the proportions of projectile and target-rock components. Our results from the CBIS contrast with those from the Chicxulub crater, where there is little or no evidence for the

  2. Micro-structural strengthening mechanism of multiple laser shock processing impacts on AISI 8620 steel

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J.Z. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Zhong, J.W., E-mail: zjw1033@126.com [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Luo, K.Y.; Zhang, L.; Dai, F.Z. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Chen, K.M. [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Q.W.; Zhong, J.S.; Zhang, Y.K. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China)

    2011-07-25

    Highlights: {yields} LSP can clearly refine coarse grains in the shocked region by dislocation movement. {yields} Micro-structural evolution of AISI 8620 steel after LSP impacts is revealed. {yields} LSP on AISI 8620 steel have grain refinement and dispersion strengthening of carbon. {yields} The results can provide some insights on surface modification of low carbon steel. - Abstract: Micro-structural evolution in the near-surface region of AISI 8620 steel subjected to multiple laser shock processing (LSP) impacts were investigated by means of cross-sectional optical microscopy (OM) and transmission electron microscopy (TEM) observations. Micro-structural evolution process subjected to multiple LSP impacts can be described as follows: (i) the parallel lamellar pearlites are broken into bitty pearlites, and dislocation activities simultaneously led to the formation of dislocation lines (DLs) and dislocation pile-ups in original grains; (ii) bitty pearlites were all broken into Fe{sub 3}C granules, and dislocation movement made Fe{sub 3}C granules disperse near subgrain boundaries and led to subgrain boundaries separating individual cells, and (iii) subgrain boundaries were refined to grain boundaries. Multiple LSP impacts on AISI 8620 steel had dual-function: the refinement of coarse grains in the near-surface region by dislocation movement and dispersion strengthening of C atoms which cut cementite and diffused into the ferrite by moving dislocations.

  3. Experimental and Numerical Investigation of Wide Area Blunt Impact Damage to Composite Aircraft Structures

    Science.gov (United States)

    Chen, Zhi Ming

    Due to their high performance and weight efficiency, carbon fiber composites are increasingly being used in aircraft primary structure applications. Exposed composite structures (e.g., fuselage lower body) are susceptible accidental impacts by ground service equipment (GSE). The very high mass (over 10,000 kg) of GSE impact can involve high energy (over 1000 J) and thus can induce significant internal damage. Furthermore, the large contact area potentially involved with GSE impact can create significant internal delamination and fiber failure without leaving exterior-visible signs that any damage has occurred. The objectives of the research described herein are to: (1) conduct experimental investigation into the composite aircraft damage caused by GSE impact, (2) examine the small-scale failure modes in focused, element-level studies, (3) establish a finite element modeling methodology involving detailed simulation capability that is validated via small-scale tests, and (4) apply these modeling capabilities to accurately predict full-scale structural behavior without adjustment (e.g., tuning) of modeling input parameters.

  4. Projectiles Impact Assessment of Aircraft Wing Structures with Real Dynamic Load

    Science.gov (United States)

    Han, Lu; Han, Qing; Wang, Changlin

    2015-07-01

    This paper presents an analysis to achieve the impact damage of the wing structure under real dynamic load. MPCCI tools are utilized to convert wing aerodynamic load into structural Finite Element Method (FEM) node load. The ANSYS/LS-DYNA code is also used to simulate the dynamic loading effects of the wing structure hit by several projectiles, including both active damage mechanism and common damage mechanism. In addition, structural node force on the leading edge and the midline is compared to the aerodynamic load separately. Furthermore, the statistical analysis of the penetrating size and the stress concentration around the damage holes indicates that under the same load situation, the structural damage efficiency of active damage mechanism is significantly higher than the one of common damage mechanism.

  5. Structure and conformation of peptides at air/aqueous interface and their impact on interfacial water structure

    Science.gov (United States)

    Chandra Jena, Kailash; Tomar, Deepak

    Process of protein folding is very essential for the proper functioning of the protein molecules at membrane surface and other organelles. Understanding the process of protein folding at various biological relevant aqueous interfaces are very important to understand various complicated chemical and physical processes relevant to chemistry, physics, and medicine. The building blocks of proteins molecules are amino acids and the chemistry of each amino acid is very different; as a consequence their sequence plays an important role for various conformations upon adsorption for the protein molecules. In the present study, we have investigated the interfacial structure and conformation of two amino acids (L-Proline and L-Tyrosine) and peptide molecules formed from these two amino acids (L-Tyr-Pro). We have used sum frequency generation (SFG) vibrational spectroscopy to probe the air/aqueous interface. We have studied the impact of adsorption of the amino acids and the peptide molecules on the interfacial water structure by slowly varying concentration and ionic strength of the solutions. Our preliminary result shows a huge impact of the adsorption process of peptide molecules on the hydrogen bonding environment of interfacial structure of water. Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab-140001.

  6. Newly identified "Tunnunik" impact structure, Prince Albert Peninsula, northwestern Victoria Island, Arctic Canada

    Science.gov (United States)

    Dewing, Keith; Pratt, Brian R.; Hadlari, Thomas; Brent, Tom; BÉDard, Jean; Rainbird, Robert H.

    2013-02-01

    Regional geological mapping of the glaciated surface of northwestern Victoria Island in the western Canadian Arctic revealed an anomalous structure in otherwise flat-lying Neoproterozoic and lower Paleozoic carbonate rocks, located south of Richard Collinson Inlet. The feature is roughly circular in plan view, approximately 25 km in diameter, and characterized by quaquaversal dips of approximately 45°, decreasing laterally. The core of the feature also exhibits local vertical dips, low-angle reverse faults, and drag folds. Although brecciation was not observed, shatter cones are pervasive in all lithologies in the central area, including 723 Ma old dikes that penetrate Neoproterozoic limestones. Their abundance decreases distally, and none was observed in surrounding, horizontally bedded strata. This circular structure is interpreted as a deeply eroded meteorite impact crater of the complex type, and the dipping strata as the remnants of the central uplift. The variation in orientation and shape of shatter cones point to variably oriented stresses with the passage of the shock wave, possibly related to the presence of pore water in the target strata as well as rock type and lithological heterogeneities, especially bed thickness. Timing of impact is poorly constrained. The youngest rocks affected are Late Ordovician (approximately 450 Ma) and the impact structure is mantled by undisturbed postglacial sediments. Regional, hydrothermal dolomitization of the Ordovician limestones, possibly in the Late Devonian (approximately 360 Ma), took place before the impact, and widespread WSW-ENE-trending normal faults of probable Early Cretaceous age (approximately 130 Ma) apparently cross-cut the impact structure.

  7. A modified Kelvin impact model for pounding simulation of base-isolated building with adjacent structures

    Institute of Scientific and Technical Information of China (English)

    Ye Kun; Li Li; Zhu Hongping

    2009-01-01

    Base isolation can effectively reduce the seismic forces on a superstructure, particularly in low- to medium-rise buildings. However, under strong near-fault ground motions, pounding may occur at the isolation level between the base-isolated building (BIB) and its surrounding retaining walls. To effectively investigate the behavior of the BIB pounding with adjacent structures, after assessing some commonly used impact models, a modified Kelvin impact model is proposed in this paper. Relevant parameters in the modified Kelvin model are theoretically derived and numerically verified through a simple pounding case. At the same time, inelasticity of the isolated superstructure is introduced in order to accurately evaluate the potential damage to the superstructure caused by the pounding of the BIB with adjacent structures. The reliability of the modified Kelvin impact model is validated through numerical comparisons with other impact models. However, the difference between the numerical results from the various impact analytical models is not significant. Many numerical simulations of BIBs are conducted to investigate the influence of various design parameters and conditions on the peak inter-story drills and floor accelerations during pounding. It is shown that pounding can substantially increase floor accelerations, especially at the ground floor where impacts occur. Higher modes of vibration are excited during poundings, increasing the inter-story drifts instead of keeping a nearly rigid-body motion of the superstructure. Furthermore, higher ductility demands can be imposed on lower floors of the superstructure. Moreover, impact stiffness seems to play a significant role in the acceleration response at the isolation level and the inter-story drifts of lower floors of the superstructure. Finally, the numerical results show that excessive flexibility of the isolation system used to minimize the floor accelerations may cause the BIB to be more susceptible to pounding

  8. Sediment distribution modeling for evaluating the impact of initial structure on catchment hydrological behaviour

    Science.gov (United States)

    Maurer, T. J.; Gerke, H. H.; Hinz, C.

    2015-12-01

    Structural heterogeneity, namely the spatial distribution of soils and sediments (represented by mineral particles), characterizes catchment hydrological behavior. In natural catchments, local geology and the specific geomorphic processes determine the characteristics and spatial distribution of structures. In constructed catchments, structural features are determined primarily by the construction processes and the geological origin of the parent material. Objectives are scenarios of 3D catchment structures in form of complete 3D description of soil hydraulic properties generated from the knowledge of the formation processes. The constructed hydrological catchment 'Hühnerwasser' (Lower Lusatia, Brandenburg, Germany) was used for the calibration and validation of model results due to its well-known conditions. For the modeling of structural features, a structure generator was used to model i) quasi-deterministic sediment distributions using input data from a geological model of the parent material excavation site; ii) sediment distributions that are conditioned to measurement data from soil sampling; and iii) stochastic component sediment distributions. All three approaches allow a randomization within definable limits. Furthermore, the spoil cone / spoil ridge orientation, internal layering, surface compaction and internal spoil cone compaction were modified. These generated structural models were incorporated in a gridded 3D volume model constructed with the GOCAD software. The impact of structure variation was assessed by hydrological modeling with HYDRUS 2D/3D software. 3D distributions of soil hydraulic properties were estimated based on generated sediment properties using adapted pedotransfer functions. Results were compared with hydrological monitoring data. The impact of structural feature variation on hydrological behavior was analyzed by comparing different simulation scenarios. The established initial sediment distributions provide a basis for the

  9. Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

    Science.gov (United States)

    Ryan, S.; Ordonez, E.; Christiansen, E. L.; Lear, D. M.

    2010-01-01

    Open cell metallic foam core sandwich panel structures are of interest for application in spacecraft micrometeoroid and orbital debris shields due to their novel form and advantageous structural and thermal performance. Repeated shocking as a result of secondary impacts upon individual foam ligaments during the penetration process acts to raise the thermal state of impacting projectiles ; resulting in fragmentation, melting, and vaporization at lower velocities than with traditional shielding configurations (e.g. Whipple shield). In order to characterize the protective capability of these structures, an extensive experimental campaign was performed by the Johnson Space Center Hypervelocity Impact Technology Facility, the results of which are reported in this paper. Although not capable of competing against the protection levels achievable with leading heavy shields in use on modern high-risk vehicles (i.e. International Space Station modules), metallic foam core sandwich panels are shown to provide a substantial improvement over comparable structural panels and traditional low weight shielding alternatives such as honeycomb sandwich panels and metallic Whipple shields. A ballistic limit equation, generalized in terms of panel geometry, is derived and presented in a form suitable for application in risk assessment codes.

  10. THE IMPACT OF CORPORATE GOVERNANCE DIMENSIONS ON FINANCIAL STRUCTURE OF THE COMPANIES IN DEVELOPING COUNTRIES

    Directory of Open Access Journals (Sweden)

    IONESCU ALIN

    2014-12-01

    Full Text Available Corporate governance represents a current topic for academic community and practitioners, in the context of globalization and crisis, especially in case of developing countries. The main purpose of this paper is to analyze which dimensions of corporate governance are able to exercise a significant impact on the companies’ financial structure, using a dataset with 77 developing countries from Africa, Asia, Latin America and Central and Eastern Europe. The data are provided from World Bank Enterprise Survey website and the variables are grouped in two directions: corporate governance and financial structure variables. In this regard, using principal components analysis approach, we grouped firstly the variables related to financial structure and then variables related to the main four dimensions of corporate governance, such as ownership structure and management quality, transparency, environment and corruption. The impact of corporate governance dimensions on companies’ financial structure was analyzed in a generalized linear model framework and the main result of this paper consists in the fact that, for analyzed countries, companies’ financial structure is significantly influenced by several dimensions of the governance like transparency, environment or corruption.

  11. THE IMPACT OF CORPORATE GOVERNANCE DIMENSIONS ON FINANCIAL STRUCTURE OF THE COMPANIES IN DEVELOPING COUNTRIES

    Directory of Open Access Journals (Sweden)

    IONESCU ALIN

    2014-12-01

    Full Text Available Corporate governance represents a current topic for academic community and practitioners, in the context of globalization and crisis, especially in case of developing countries. The main purpose of this paper is to analyze which dimensions of corporate governance are able to exercise a significant impact on the companies’ financial structure, using a dataset with 77 developing countries from Africa, Asia, Latin America and Central and Eastern Europe. The data are provided from World Bank Enterprise Survey website and the variables are grouped in two directions: corporate governance and financial structure variables. In this regard, using principal components analysis approach, we grouped firstly the variables related to financial structure and then variables related to the main four dimensions of corporate governance, such as ownership structure and management quality, transparency, environment and corruption. The impact of corporate governance dimensions on companies’ financial structure was analyzed in a generalized linear model framework and the main result of this paper consists in the fact that, for analyzed countries, companies’ financial structure is significantly influenced by several dimensions of the governance like transparency, environment or corruption

  12. Evaluation of underground pipe-structure interface for surface impact load

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shen, E-mail: swang@terrapower.com

    2017-06-15

    Highlights: • A simple method is proposed for the evaluation of underground pipelines for surface impact load considering the effect of a nearby pipe-structure interface. • The proposed simple method can be used to evaluate the magnitude of damage within a short period of time after accidental drop occurs. • The proposed method is applied in a practical example and compared by using finite element analysis. - Abstract: Nuclear safety related buried pipelines need to be assessed for the effects of postulated surface impact loads. In published solutions, the buried pipe is often considered within an elastic half space without interference with other underground structures. In the case that a surface impact occurs in short distance from an underground pipe-structure interface, this boundary condition will further complicate the buried pipe evaluation. Neglecting such boundary effect in the assessment may lead to underestimating potential damage of buried pipeline, and jeopardizing safety of the nuclear power plant. Comprehensive analysis of such structure-pipe-soil system is often subjected to availability of state-of-art finite element tools, as well as costly and time consuming. Simple, but practical conservative techniques have not been established. In this study, a mechanics based solution is proposed in order to assess the magnitude of damage to a buried pipeline beneath a heavy surface impact considering the effect of a nearby pipe-structure interface. The proposed approach provides an easy to use tool in the early stage of evaluation before the decision of applying more costly technique can be made by owner of the nuclear facility.

  13. The impact of information technology on productivity using structural equations technique in Iran Behnoush Company

    Directory of Open Access Journals (Sweden)

    Mina Beig

    2012-08-01

    Full Text Available Information technology plays an important role on increasing productivity in many organizations. The primary objective of the present survey is to study the impact of information technology on productivity and find a positive and significant relationship between these two factors. Structural equations technique and LISREL software are used for analysis of the questionnaires distributed among managers and some employees of Iran Behnoush Company. Organizations try to improve their performance by investment in information technology. However, many of the previous studies indicate insignificance of the impact of information technology on productivity of the organizations. The present survey studies the impact of information technology on organizations' productivity through the collected data from the above company. Results confirm existence of a positive relationship between information technology and productivity.

  14. Anthropogenic impacts on tropical forest biodiversity: a network structure and ecosystem functioning perspective.

    Science.gov (United States)

    Morris, Rebecca J

    2010-11-27

    Huge areas of diverse tropical forest are lost or degraded every year with dramatic consequences for biodiversity. Deforestation and fragmentation, over-exploitation, invasive species and climate change are the main drivers of tropical forest biodiversity loss. Most studies investigating these threats have focused on changes in species richness or species diversity. However, if we are to understand the absolute and long-term effects of anthropogenic impacts on tropical forests, we should also consider the interactions between species, how those species are organized in networks, and the function that those species perform. I discuss our current knowledge of network structure and ecosystem functioning, highlighting empirical examples of their response to anthropogenic impacts. I consider the future prospects for tropical forest biodiversity, focusing on biodiversity and ecosystem functioning in secondary forest. Finally, I propose directions for future research to help us better understand the effects of anthropogenic impacts on tropical forest biodiversity.

  15. Impact and structure of literature on nanoparticle generation by laser ablation in liquids

    Science.gov (United States)

    Barcikowski, Stephan; Devesa, Francisco; Moldenhauer, Kirsten

    2009-11-01

    The number of publications on laser ablation and nanoparticle generation in liquids increased by the factor of 15 in the last decade, with comparable high impact of the most cited articles in this field. A nearly unlimited variety of nanoparticle material, liquid matrix, and conjugative agent can be combined to a huge variety of colloids within a few minutes of laser processing. However, this diversification makes it hard to identify main research directions without a comprehensive literature overview. This investigation evaluates the impact and structure of the literature in this field tagging most prolific subjects and articles. Using an optimized search algorithm, the data sets derived from Science Citation Index (1998-2008) allow for statements on publication subject clusters, impact of articles and journals, as well as mapping global spots of activities.

  16. IRIS-2012 OECD/NEA/CSNI benchmark: Numerical simulations of structural impact

    Energy Technology Data Exchange (ETDEWEB)

    Orbovic, Nebojsa, E-mail: nebojsa.orbovic@cnsc-ccsn.gc.ca [Canadian Nuclear Safety Commission, Ottawa, ON (Canada); Tarallo, Francois [IRSN, Fontenay aux Roses (France); Rambach, Jean-Mathieu [Géodynamique et Structures, Bagneux (France); Sagals, Genadijs; Blahoianu, Andrei [Canadian Nuclear Safety Commission, Ottawa, ON (Canada)

    2015-12-15

    A benchmark of numerical simulations related to the missile impact on reinforced concrete (RC) slabs has been launched in the frame of OECD/NEA/CSNI research program “Improving Robustness Assessment Methodologies for Structures Impacted by Missiles”, under the acronym IRIS. The goal of the research program is to simulate RC structural, flexural and punching, behavior under deformable and rigid missile impact. The first phase called IRIS-2010 was a blind prediction of the tests performed at VTT facility in Espoo, Finland. The two simulations were performed related to two series of tests: (1) two tests on the impact of a deformable missile exhibiting damage mainly by flexural (so-called “flexural tests”) or global response and (2) three tests on the impact of a rigid missile exhibiting damage mainly by punching response (so-called “punching tests”) or local response. The simulation results showed significant scatter (coefficient of variation up to 132%) for both flexural and punching cases. The IRIS-2012 is the second, post-test, phase of the benchmark with the goal to improve simulations and reduce the scatter of the results. Based on the IRIS-2010 recommendations and to better calibrate concrete constitutive models, a series of tri-axial tests as well as Brazilian tests were performed as a part of the IRIS-2012 benchmark. 25 teams from 11 countries took part in this exercise. Majority of participants were part of the IRIS-2010 benchmark. Participants showed significant improvement in reducing epistemic uncertainties in impact simulations. Several teams presented both finite element (FE) and simplified analysis as per recommendations of the IRIS-2010. The improvements were at the level of simulation results but also at the level of understanding of impact phenomena and its modeling. Due to the complexity of the physical phenomena and its simulation (high geometric and material non-linear behavior) and inherent epistemic and aleatory uncertainties, the

  17. New links between the Chicxulub impact structure and the Cretaceous/Tertiary boundary

    Science.gov (United States)

    Sharpton, V.L.; Dalrymple, G.B.; Marin, L.E.; Ryder, G.; Schuraytz, B.C.; Urrutia-Fucugauchi, J.

    1992-01-01

    THE 200-km-diameter Chicxulub structure1-3 in northern Yucatan, Mexico has emerged as the prime candidate for the Cretaceous/Tertiary (K/T) boundary impact crater3-6. Concentric geophysical anomalies associated with enigmatic occurrences of Upper Cretaceous breccias and andesitic rocks led Penfield and Camargo1 to suspect that this structure was a buried impact basin. More recently, the discovery of shocked quartz grains in a Chicxulub breccia3, and chemical similarities between Chicxulub rocks and K/T tektite-like glasses3-6 have been advanced as evidence that the Chicxulub structure is a K/T impact site. Here we present evidence from core samples that Chicxulub is indeed a K/T source crater, and can apparently account for all the evidence of impact distributed globally at the K/T boundary without the need for simultaneous multiple impacts or comet showers. Shocked breccia clasts found in the cores are similar to shocked lithic fragments found worldwide in the K/T boundary ejecta layer7,8. The Chicxulub melt rocks that we studied contain anomalously high levels of iridium (up to 13.5 parts per 109), also consistent with the indium-enriched K/T boundary layer9. Our best estimate of the crystallization age of these melt rocks, as determined by 40Ar/39Ar analyses, is 65.2??0.4 (1??) Myr, in good agreement with the mean plateau age of 64.98 ?? 0.05 Myr recently reported10. Furthermore, these melt rocks acquired a remanent magnetization indicating that they cooled during an episode of reversed geomagnetic polarity. The only such episode consistent with 40Ar/39Ar constraints is chron 29R, which includes the K/T boundary.

  18. Evidence for a spatially extensive hydrothermal system at the Ries impact structure, Germany

    Science.gov (United States)

    Sapers, H. M.; Osinski, G. R.; Flemming, R. L.; Buitenhuis, E.; Banerjee, N. R.; Tornabene, L. L.; Blain, S.; Hainge, J.

    2017-02-01

    The 15 Ma, 26 km diameter Ries impact structure in south-central Germany was one of the first terrestrial impact structures where evidence of impact-associated hydrothermal alteration was recognized. Previous studies suggested that pervasive, high-temperature hydrothermal activity was restricted to the area within the "inner ring" (i.e., the crater-fill impactite units). Here we present mineralogical evidence for localized hydrothermal activity in the ejecta beyond the crater rim in two previously unstudied settings: a pervasively altered lens of suevite ejecta directly overlying the Bunte Breccia at the Aumühle quarry; and suevite ejecta at depth overlain by 20 m of lacustrine sediments sampled by the Wörnitzostheim 1965 drill core. A comprehensive set of X-ray diffraction analyses indicates five distinct alteration regimes (1) surficial ambient weathering characterized by smectite and a minor illitic component; (2) locally restricted hydrothermal activity characterized by an illitic component and minor smectite; (3) hydrothermal activity at depth characterized by smectite, a minor illitic component, and calcite; (4) hydrothermal activity at depth characterized by smectite, a minor illitic component, calcite, zeolites, and clinochlore; and (5) pervasive hydrothermal activity at depth characterized by smectite, a minor illitic component, and minor clinochlore. These data spatially extend the Ries postimpact hydrothermal system suggesting a much more extensive, complex, and dynamic system than previously thought. Constraining the mineralogical alteration regimes at the Ries impact structure may also further our understanding of impact-associated phyllosilicate formation on Mars with implications for climate models and habitability.

  19. Development of an ultrasonic nondestructive inspection method for impact damage detection in composite aircraft structures

    Science.gov (United States)

    Capriotti, M.; Kim, H. E.; Lanza di Scalea, F.; Kim, H.

    2017-04-01

    High Energy Wide Area Blunt Impact (HEWABI) due to ground service equipment can often occur in aircraft structures causing major damages. These Wide Area Impact Damages (WAID) can affect the internal components of the structure, hence are usually not visible nor detectable by typical one-sided NDE techniques and can easily compromise the structural safety of the aircraft. In this study, the development of an NDI method is presented together with its application to impacted aircraft frames. The HEWABI from a typical ground service scenario has been previously tested and the desired type of damages have been generated, so that the aircraft panels could become representative study cases. The need of the aircraft industry for a rapid, ramp-friendly system to detect such WAID is here approached with guided ultrasonic waves (GUW) and a scanning tool that accesses the whole structure from the exterior side only. The wide coverage of the specimen provided by GUW has been coupled to a differential detection approach and is aided by an outlier statistical analysis to be able to inspect and detect faults in the challenging composite material and complex structure. The results will be presented and discussed with respect to the detection capability of the system and its response to the different damage types. Receiving Operating Characteristics curves (ROC) are also produced to quantify and assess the performance of the proposed method. Ongoing work is currently aimed at the penetration of the inner components of the structure, such as shear ties and C-frames, exploiting different frequency ranges and signal processing techniques. From the hardware and tool development side, different transducers and coupling methods, such as air-coupled transducers, are under investigation together with the design of a more suitable scanning technique.

  20. Vibration Control of Structures using Vibro-Impact Nonlinear Energy Sinks

    Directory of Open Access Journals (Sweden)

    M. Ahmadi

    2016-09-01

    Full Text Available Using Vibro-Impact Nonlinear Energy Sinks (VI NESs is one of the novel strategies to control structural vibrations and mitigate their seismic response. In this system, a mass is tuned on the structure floor, so that it has a specific distance from an inelastic constraint connected to the floor mass. In case of structure stimulation, the displaced VI NES mass collides with the  inelastic constraint and upon impacts, energy is dissipated. In the present work, VI NES is studied when its parameters, including clearance and stiffness ratio, are simultaneously optimized. Harmony search as a recent meta-heuristic algorithm is efficiently specialized and utilized for the aforementioned continuous optimization problem. The optimized attached VI NES is thus shown to be capable of interacting with the primary structure over a wide range of frequencies. The resulting controlled response is then investigated, in a variety of low and medium rise steel moment frames, via nonlinear dynamic time history analyses. Capability of the VI NES to dissipate siesmic input energy of earthquakes and their capabilitiy in reducing response of srtructures effectively, through vibro-impacts between the energy sink’s mass and the floor mass, is discussed by extracting several performance indices and the corresponding Fourier spectra. Results of the numerical simulations done on some structural model examples reveal that the optimized VI NES has caused successive redistribution of energy from low-frequency high-amplitude vibration modes to high-frequency low-amplitude modes, bringing about the desired attenuation of the structural responses.

  1. Market impact and structure dynamics of the Chinese stock market based on partial correlation analysis

    Science.gov (United States)

    Li, Xing; Qiu, Tian; Chen, Guang; Zhong, Li-Xin; Wu, Xiao-Run

    2017-04-01

    Partial correlation analysis is employed to study the market impact on the Chinese stock market from both the native and external markets. Whereas the native market index is observed to have a great impact on the market correlations for both the Shanghai and Shenzhen stock markets, some external stock indices of the United States, European and Asian stock markets show a slight influence on the Chinese market. The individual stock can be affected by different economic sectors, but the dominant influence is from the sector the stock itself belongs to or closely related to, and the finance and insurance sector shows a weaker correlation with other economic sectors. Moreover, the market structure similarity exhibits a negative correlation with the price return in most time, and the structure similarity decays with the time interval.

  2. Protecting Offshore Wind Turbines against Ship Impacts by Means of Adaptive Inflatable Structures

    Directory of Open Access Journals (Sweden)

    Cezary Graczykowski

    2009-01-01

    Full Text Available Collisions with small service ships are serious danger for offshore wind turbines. Installing torus-shaped adaptive inflatable structure that surrounds a wind turbine tower at water level is one method of effective protection. Proposed pneumatic structure contains several separate air chambers equipped with devices for fast inflation and pressure release. The system can be adapted to various impact scenarios by adjusting the level of initial pressure in each chamber and by controlling the release of compressed air during collision. The paper presents finite element simulation of ship collision with wind turbine tower protected by pneumatic structure, conducted using ABAQUS software. Introduced methods of pressure adjustment are aimed at mitigating tower and ship response. The performed feasibility study proves that inflatable structure can effectively protect the wind turbine tower and the ship against serious damage.

  3. IMPACT OF THE GLOBAL CRISIS ON THE GOVERNANCE STRUCTURES OF INTERNATIONAL FINANCIAL INSTITUTIONS

    Directory of Open Access Journals (Sweden)

    Gökhan Özkan

    2011-11-01

    Full Text Available The global financial crisis dragged many countries into recession, demonstrated that the internationalfinancial system has structural problems and started discussions about restructuring of the international financialinstitutions. The main objective of this paper is to investigate the impact of the global financial crisis on thegovernance structures of the international financial institutions. To this end, studies made at different internationalplatforms were evaluated. The debates and negotiations among the developed and developing countries aboutgovernance structures of the international financial institutions were analyzed. Developing countries’ demand toreform the decision-making mechanisms of the Bretton Woods institutions, the IMF and the World Bank anddeveloped countries’ reservations were investigated. It was concluded that the new shape of the internationalfinancial architecture and governance structures of international financial institutions will depend on internationalpolitics as well as the evolution of the global crisis and the economic dynamics.

  4. Impact of organizational structure on vaccination of first responders: a case study.

    Science.gov (United States)

    McGuire-Wolfe, Christine

    2011-01-01

    The experience of H1N1 vaccine delivery to public safety personnel in a suburban county in Florida suggests a relationship between the degree of hierarchy of an agency and successful implementation of a vaccination program for novel 2009 H1N1 influenza virus. This case study describes the structural organization of the Sheriff's Office and Fire Rescue in County X, provides timelines for vaccine program implementation and numbers of personnel vaccinated, and illustrates the impact of autonomy on the timeliness of vaccine implementation. An "emergency approval pathway" is recommended for organizations or departments that are likely to encounter delays in disaster or pandemic response due to organizational structure.

  5. Influence of Thermal Homogenization Treatment on Structure and Impact Toughness of H13 ESR Steel

    Institute of Scientific and Technical Information of China (English)

    MA Dang-shen; ZHOU Jian; CHEN Zai-zhi; ZHANG Zhong-kan; CHEN Qi-an; LI De-hui

    2009-01-01

    The as-cast microstrueture of H13 ESR ingot and the influence of high temperature diffusion treatment on the structure and impact toughness have been investigated. The results show that the dendrite arm spacing gradually becomes wide from the surface to the center of ingot, and the large primary carbide particles always exist in interdendritic segregation areas; by means of high temperature diffusion treatment of ingot prior to hot forging, the banded segregation is nearly eliminated, the annealed structure is more uniform and the isotropic properties have been improved remarkably.

  6. The impact of family structure on the health of children: Effects of divorce.

    Science.gov (United States)

    Anderson, Jane

    2014-11-01

    Nearly three decades of research evaluating the impact of family structure on the health and well-being of children demonstrates that children living with their married, biological parents consistently have better physical, emotional, and academic well-being. Pediatricians and society should promote the family structure that has the best chance of producing healthy children. The best scientific literature to date suggests that, with the exception of parents faced with unresolvable marital violence, children fare better when parents work at maintaining the marriage. Consequently, society should make every effort to support healthy marriages and to discourage married couples from divorcing.

  7. The impact of structural diversity and parameterization on maps of the protein universe.

    Science.gov (United States)

    Asarnow, Daniel; Singh, Rahul

    2013-12-20

    Low dimensional maps of protein structure space (MPSS) provide a powerful global representation of all proteins. In such mappings structural relationships are depicted through spatial adjacency of points, each of which represents a molecule. MPSS can help in understanding the local and global topological characteristics of the structure space, as well as elucidate structure-function relationships within and between sets of proteins. A number of meta- and method-dependent parameters are involved in creating MPSS. However, at the state-of-the-art, a systematic investigation of the influence of these parameters on MPSS construction has yet to be carried out. Further, while specific cases in which MPSS out-perform pairwise distances for prediction of functional annotations have been noted, no general explanation for this phenomenon has yet been advanced. We address the above questions within the technical context of creating MPSS by utilizing multidimensional scaling (MDS) for obtaining low-dimensional projections of structure alignment distances. MDS is demonstrated as an effective method for construction of MPSS where related structures are co-located, even when their functional and evolutionary proximity cannot be deduced from distributions of pairwise comparisons alone. In particular, we show that MPSS exceed pairwise distance distributions in predictive capability for those annotations of shared function or origin which are characterized by a high level of structural diversity. We also determine the impact of the choice of structure alignment and MDS algorithms on the accuracy of such predictions.

  8. Design aspects of high strength steel welded structures improved by high frequency mechanical impact (HFMI) treatment

    OpenAIRE

    Yildirim, Halid Can

    2013-01-01

    This doctoral study is concerned with the fatigue strength of welded steel structures which are improved by high frequency mechanical impact (HFMI) treatment. A comprehensive evaluation of 417 HFMI test data obtained from the literature and 24 HFMI fatigue data tested as a part of this work are studied. According to the statistical analyses an S-N slope of five (5) is proposed. A yield strength correction procedure which relates the material yield strength (fy) to fatigue is presented and ver...

  9. Double-hump resonance structure of the cross sections for electron impact ionization of Ar5+

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Configuration-average distorted-wave calculations are carried out for electron-impact ionization of Ar5+. Both direct ionization and the indirect excitation autoionization processes are included in our calculations. Our theoretical values are in quite reasonable agreement with the experimental data. The indirect processes contribute up to 50% to the total ionization cross sections. The possible origin of double-hump resonance structure of the cross sections is demonstrated and the contributions of metastable states are also taken into account.

  10. THE IMPACT OF CORPORATE GOVERNANCE DIMENSIONS ON FINANCIAL STRUCTURE OF THE COMPANIES IN DEVELOPING COUNTRIES

    OpenAIRE

    IONESCU ALIN; TUDOREANU PETRU

    2014-01-01

    Corporate governance represents a current topic for academic community and practitioners, in the context of globalization and crisis, especially in case of developing countries. The main purpose of this paper is to analyze which dimensions of corporate governance are able to exercise a significant impact on the companies’ financial structure, using a dataset with 77 developing countries from Africa, Asia, Latin America and Central and Eastern Europe. The data are provided from World Bank Ente...

  11. Small x nonlinear evolution with impact parameter and the structure function data

    CERN Document Server

    Berger, Jeffrey

    2011-01-01

    Nonlinear evolution at small values of Bjorken x is evaluated numerically using the dipole framework with impact parameter dependence. Confinement effects are modeled by including masses into the evolution. Sensitivity of the predictions due to different prescriptions of the cuts on large dipole sizes is investigated. Running coupling effects are taken into account in this analysis. Finally, a comparison with the inclusive data from HERA on the structure functions F2 and FL is performed.

  12. Tax structure in Latin American : its impact on the real economy

    OpenAIRE

    Martínez Vázquez, Jorge; Vulovic, Violeta

    2014-01-01

    In this paper we review the structure of tax systems in Latin America and analyze their impact on the real economy - economic growth, macro-economic stability, and income redistribution. We find that in Latin America relatively higher reliance on direct taxes slows economic growth, although this effect is smaller than in the ‘Rest of the World.’ However, unlike in most other countries, higher reliance on direct taxes in Latin America does not appear to play a significant rol...

  13. Evaluation of computer programs used for structural analyses of impact response of spent fuel shipping casks

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, B A; Gwinn, K W

    1984-05-01

    This report presents the results of a study of impact analyses of a generic spent-fuel cask. The study compares the use and results of three different finite element computer codes. Seven different cask-like model analyses are considered. The models encompass both linear and nonlinear geometric and material behavior. On the basis of the analyses results, this report recommends what parameters are useful in the comparison of different structural finite element computer programs. 5 references, 36 figures, 11 tables.

  14. Impact of distribution intensity on perceived quality, brand awareness and brand loyality - structural model

    OpenAIRE

    Ivan-Damir Anić; Edo Rajh

    2008-01-01

    The purpose of this empirical study was to determine the impacts of distribution intensity on perceived quality and brand awareness, and to analyze the effects of perceived quality and brand awareness on brand loyalty. A structural equation model was used to identify the size and the direction of proposed relationships. The model was tested on a sample of 956 students using three brand categories in the manufacturing industry and three brand categories in the service industry. The proposed hy...

  15. Impact of new computing systems on computational mechanics and flight-vehicle structures technology

    Science.gov (United States)

    Noor, A. K.; Storaasli, O. O.; Fulton, R. E.

    1984-01-01

    Advances in computer technology which may have an impact on computational mechanics and flight vehicle structures technology were reviewed. The characteristics of supersystems, highly parallel systems, and small systems are summarized. The interrelations of numerical algorithms and software with parallel architectures are discussed. A scenario for future hardware/software environment and engineering analysis systems is presented. Research areas with potential for improving the effectiveness of analysis methods in the new environment are identified.

  16. The first large meteorite impact structure discovered in the Middle East: Jebel Waqf as Suwwan, Jordan

    Science.gov (United States)

    Salameh, E.; Khoury, H.; Reimold, W. U.; Schneider, W.

    2008-10-01

    Triggered by re-evaluation of a 1960s report on the regional geology of the northeastern border region of Jordan and following Landsat satellite image investigation, a 5.5 km diameter, complex, circular structure was discovered in the central eastern region of the Kingdom of Jordan. Initial ground truthing revealed complex geological structures involving Upper Cretaceous and Paleogene strata, and including a prominent outer rim rising up to 60 m above the surrounding plain, an intermediate ring of up to 20 m elevation within a ring syncline, and a central zone of stratigraphically uplifted sedimentary strata characterized by intense macroscopic (folding and faulting, widespread cataclasis) and locally mesoscopic (cataclasis) deformation. Ten sites with shatter cone development in fine-grained sandstone or limestone have been mapped to date, mostly in the outer parts of the central uplifted area. This finding confirms that the Jebel Waqf as Suwwan structure was formed as the result of the impact of an extraterrestrial projectile. Search for impactdiagnostic micro-deformation has been rather unsuccessful: only 1 quartz grain with both planar deformation features and planar fractures has been detected in a sandstone sample to date. The overall majority of the approximately 70 samples investigated by micropetrographic analysis consist of extremely fine-grained chert, siltstone, or marly limestone. Cataclasis is widespread in chert and limestone, also on the micro-scale. Considering the severely limited amount of characteristic impact microdeformation, and the stratigraphic situation within the central uplift, it is likely that a relatively deep level of the central uplift is currently exposed. The extensive drainage demonstrated for this region supports the conclusion that this impact structure could be quite deeply eroded—especially as its geology involves some relatively soft lithologies (marls, limestones). The age of this impact event is at present poorly

  17. The Impact of Structural Vibration on Flying Qualities of a Supersonic Transport

    Science.gov (United States)

    Raney, David L.; Jackson, E. Bruce; Buttrill, Carey S.; Adams, William M.

    2001-01-01

    A piloted simulation experiment has been conducted in the NASA Langley Visual/Motion Simulator facility to address the impact of dynamic aeroelastic effects on flying qualities of a supersonic transport. The intent of this experiment was to determine the effectiveness of several measures that may be taken to reduce the impact of aircraft flexibility on piloting tasks. Potential solutions that were examined included structural stiffening, active vibration suppression, and elimination of visual cues associated with the elastic modes. A series of parametric configurations was evaluated by six test pilots for several types of maneuver tasks. During the investigation, several incidents were encountered in which cockpit vibrations due to elastic modes fed back into the control stick through involuntary motions of the pilot's upper body and arm. The phenomenon, referred to as biodynamic coupling, is evidenced by a resonant peak in the power spectrum of the pilot's stick inputs at a structural mode frequency. The results of the investigation indicate that structural stiffening and compensation of the visual display were of little benefit in alleviating the impact of elastic dynamics on the piloting tasks, while increased damping and elimination of control-effector excitation of the lowest frequency modes offered great improvements when applied in sufficient degree.

  18. Hypervelocity impact testing of advanced materials and structures for micrometeoroid and orbital debris shielding

    Science.gov (United States)

    Ryan, Shannon; Christiansen, Eric L.

    2013-02-01

    A series of 66 hypervelocity impact experiments have been performed to assess the potential of various materials (aluminium, titanium, copper, stainless steel, nickel, nickel/chromium, reticulated vitreous carbon, silver, ceramic, aramid, ceramic glass, and carbon fibre) and structures (monolithic plates, open-cell foam, flexible fabrics, rigid meshes) for micrometeoroid and orbital debris (MMOD) shielding. Arranged in various single-, double-, and triple-bumper configurations, screening tests were performed with 0.3175 cm diameter Al2017-T4 spherical projectiles at nominally 6.8 km/s and normal incidence. The top performing shields were identified through target damage assessments and their respective weight. The top performing candidate shield at the screening test condition was found to be a double-bumper configuration with a 0.25 mm thick Al3003 outer bumper, 6.35 mm thick 40 PPI aluminium foam inner bumper, and 1.016 mm thick Al2024-T3 rear wall (equal spacing between bumpers and rear wall). In general, double-bumper candidates with aluminium plate outer bumpers and foam inner bumpers were consistently found to be amongst the top performers. For this impact condition, potential weight savings of at least 47% over conventional all-aluminium Whipple shields are possible by utilizing the investigated materials and structures. The results of this study identify materials and structures of interest for further, more in-depth, impact investigations.

  19. Assessing the cumulative impact of disturbance on canopy structure and chemistry in Appalachian forests

    Science.gov (United States)

    Deel, Lindsay N.

    Eastern forests experience a range of disturbance events over time, from stand-replacing disturbances, such as clear cuts, to ephemeral disturbances, such as insect outbreaks. By understanding the cumulative impact of disturbances on canopy structure and chemistry, we can gain insight into management strategies, assess a variety of ecosystem services, and even contribute to a larger body of knowledge on global climate change. I transformed a series of Landsat images spanning approximately 25 years into cumulative disturbance maps covering Green Ridge State Forest and Savage River State Forest in western Maryland. Intensive field surveys collected during the summer of 2009 provided measurements of canopy N and estimates of canopy cover, understory cover, and leaf cover. I used AVIRIS imagery flown concurrently with field data collection to map canopy nitrogen across both forests. Through this project, I tested the impact of cumulative disturbance on forest canopy cover and canopy nitrogen. I found that increased values of cumulative disturbance had a measurable negative impact on forest canopy structure and canopy nitrogen. Moreover, by testing varying methods of summing cumulative disturbance, I found that past disturbances diminish over time in importance, yet still influence the current canopy structure and canopy N of a forest. Thus, my study suggests that Landsat time series data can be synthesized into cumulative metrics incorporating multiple disturbance types, which help explain important disturbance-mediated changes in ecosystem functions.

  20. Molecular dynamics study of crater formation by core-shell structured cluster impact

    Science.gov (United States)

    Aoki, Takaaki; Seki, Toshio; Matsuo, Jiro

    2012-07-01

    Crater formation processes by the impacts of large clusters with binary atomic species were studied using molecular dynamics (MD) simulations. Argon and xenon atoms are artificially organized in core-shell cluster structures with various component ratios and irradiated on a Si(1 0 0) target surface. When the cluster has Xe1000 core covered with 1000 Ar atoms, and impacts at a total of 20 keV, the core Xe cluster penetrates into the deep area, and a crater with a conical shape is left on the target. On the other hand, in the case of a cluster with the opposite structure, Ar1000 core covered with 1000 Xe atoms, the cluster stops at a shallow area of the target. The incident cluster atoms are mixed and tend to spread in a lateral direction, which results in a square shaped crater with a shallower hole and wider opening. The MD simulations suggest that large cluster impacts cause different irradiation effects by changing the structure, even if the component ratio is the same.

  1. Evidence for a Meteoritic Component in Impact Melt Rock from the Chicxulub Structure

    Science.gov (United States)

    Koeberl, Christian; Sharpton, Virgil L.; Schuraytz, Benjamin C.; Shirey, Steven B.; Blum, Joel D.; Marin, Luis E.

    1994-01-01

    The Chicxulub structure in Yucatan, Mexico, has recently been recognized as a greater then 200-km-diameter multi-ring impact crater of K-T boundary age. Crystalline impact melt rocks and breccias from within the crater, which have compositions similar to those of normal continental crustal rocks and which show shock metamorphic effects, have been studied for trace element and Re-Os isotope compositions. Re-Os isotope systematics allow the sensitive and selective determination of an extraterrestrial component in impact-derived rocks. A melt rock sample shows elevated iridium concentrations, an osmium concentration of 25 ppb, and a low Os-187/Os-188 ratio of 0.113, which are incompatible with derivation from the continental crust. Even though the Os-187/Os-188 ratio is slightly lower than the range so far measured in meteorites, a mantle origin seems unlikely for mass balance reasons and because the cratering event is unlikely to have excavated mantle material. The data support the hypothesis of a heterogeneously distributed meteoritic component in the Chicxulub melt rock. A sample of impact glass from the Haitian K-T boundary at Beloc yielded about 0.1 ppb osmium and an Os-187/0s-188 ratio of 0.251, indicating the presence of a small meteoritic component in the impact ejecta as well.

  2. Application of organic geochemistry to detect signatures of organic matter in the Haughton impact structure

    Science.gov (United States)

    Parnell, John; Lee, Pascal; Osinski, Gordon R.; Cockell, Charles S.

    2005-12-01

    Organic geochemistry applied to samples of bedrock and surface sediment from the Haughton impact structure detects a range of signatures representing the impact event and the transfer of organic matter from the crater bedrock to its erosion products. The bedrock dolomite contains hydrocarbon-bearing fluid inclusions which were incorporated before the impact event. Comparison of biomarker data from the hydrocarbons in samples inside and outside of the crater show the thermal signature of an impact. The occurrence of hydrocarbon inclusions in hydrothermal mineral samples shows that organic matter was mobilized and migrated in the immediate aftermath of the impact. The hydrocarbon signature was then transferred from bedrock to the crater-fill lacustrine deposits and present-day sediments in the crater, including wind-blown detritus in snow/ice. Separate signatures are detected from modern microbial life in crater rock and sediment samples. Signatures in Haughton crater samples are readily detectable because they include hydrocarbons generated by the burial of organic matter. This type of organic matter is not expected in crater samples on other planets, but the Haughton data show that, using very high resolution detection of organic compounds, any signature of primitive life in the crater rocks could be transferred to surface detritus and so extend the sampling medium.

  3. Melting and cataclastic features in shatter cones in basalt from the Vista Alegre impact structure, Brazil

    Science.gov (United States)

    Pittarello, Lidia; Nestola, Fabrizio; Viti, Cecilia; Crósta, Alvaro Penteado; Koeberl, Christian

    2015-07-01

    Shatter cones are one of the most widely recognized pieces of evidence for meteorite impact events on Earth, but the process responsible for their formation is still debated. Evidence of melting on shatter cone surfaces has been rarely reported in the literature from terrestrial impact craters but has been recently observed in impact experiments. Although several models for shatter cones formation have been proposed, so far, no one can explain all the observed features. Shatter cones' from the Vista Alegre impact structure, Brazil, formed in fine-grained basalt of the Jurassic-Cretaceous Serra Geral Formation (Paraná large igneous province). A continuous quenched melt film, consisting of a crystalline phase, mica, and amorphous material, decorates the striated surface. Ultracataclasites, containing subrounded pyroxene clasts in an ultrafine-grained matrix, occur subparallel to the striated surface. Several techniques were applied to characterize the crystalline phase in the melt, including Raman spectroscopy and transmission electron microscopy. Results are not consistent with any known mineral, but they do suggest a possible rare or new type of clinopyroxene. This peculiar evidence of melting and cataclasis in relation with shatter cone surfaces is interpreted as the result of tensile fracturing at the tip of a fast propagating shock-induced rupture, which led to the formation of shatter cones at the tail of the shock front, likely during the early stage of the impact events.

  4. Geochemical evidence from the Sudbury structure for crustal redistribution by large bolide impacts.

    Science.gov (United States)

    Mungall, James E; Ames, Doreen E; Hanley, Jacob J

    2004-06-03

    Deformation and melting of the crust during the formation of large impact craters must have been important during the Earth's early evolution, but such processes remain poorly understood. The 1.8-billion-year-old Sudbury structure in Ontario, Canada, is greater than 200 km in diameter and preserves a complete impact section, including shocked basement rocks, an impact melt sheet and fallback material. It has generally been thought that the most voluminous impact melts represent the average composition of the continental crust, but here we show that the melt sheet now preserved as the Sudbury Igneous Complex is derived predominantly from the lower crust. We therefore infer that the hypervelocity impact caused a partial inversion of the compositional layering of the continental crust. Using geochemical data, including platinum-group-element abundances, we also show that the matrix of the overlying clast-laden Onaping Formation represents a mixture of the original surficial sedimentary strata, shock-melted lower crust and the impactor itself.

  5. Confirmation of a meteoritic component in impact-melt rocks of the Chesapeake Bay impact structure, Virginia, USA - Evidence from osmium isotopic and PGE systematics

    Science.gov (United States)

    Lee, Seung Ryeol; Horton, J. Wright; Walker, Richard J.

    2006-06-01

    The osmium isotope ratios and platinum-group element (PGE) concentrations of impact-melt rocks in the Chesapeake Bay impact structure were determined. The impact-melt rocks come from the cored part of a lower-crater section of suevitic crystalline-clast breccia in an 823 m scientific test hole over the central uplift at Cape Charles, Virginia. The 187Os/188Os ratios of impact-melt rocks range from 0.151 to 0.518. The rhenium and platinum-group element (PGE) concentrations of these rocks are 30-270× higher than concentrations in basement gneiss, and together with the osmium isotopes indicate a substantial meteoritic component in some impact-melt rocks. Because the PGE abundances in the impact-melt rocks are dominated by the target materials, interelemental ratios of the impact-melt rocks are highly variable and nonchondritic. The chemical nature of the projectile for the Chesapeake Bay impact structure cannot be constrained at this time. Model mixing calculations between chondritic and crustal components suggest that most impact-melt rocks include a bulk meteoritic component of 0.01-0.1% by mass. Several impact-melt rocks with lowest initial 187Os/188Os ratios and the highest osmium concentrations could have been produced by additions of 0.1%-0.2% of a meteoritic component. In these samples, as much as 70% of the total Os may be of meteoritic origin. At the calculated proportions of a meteoritic component (0.01-0.1% by mass), no mixtures of the investigated target rocks and sediments can reproduce the observed PGE abundances of the impact-melt rocks, suggesting that other PGE enrichment processes operated along with the meteoritic contamination. Possible explanations are 1) participation of unsampled target materials with high PGE abundances in the impact-melt rocks, and 2) variable fractionations of PGE during syn- to post-impact events.

  6. Petrology of hydrothermal alteration in the Vargeão basaltic impact structure (South Brazil)

    Science.gov (United States)

    Yokoyama, E.; Nédélec, A.; Trindade, R. I.; Baratoux, D.; Berger, G.

    2011-12-01

    Impact cratering process is of primary importance in the evolution of solid bodies of the Solar System. But craters on basaltic rocks, which are the best analog for the surface of other planets and satellites, are rare on Earth. Most studies to date were done in the Lonar crater, a simple crater 1.8 km in diameter, formed on the basaltic flows of the Deccan Province (India). Recently, one medium-size complex crater was identified on volcanic rocks of the Paraná basin (south Brazil) and may provide additional analog to the craters of most rocky planets and satellites. The 12 km wide Vargeão is a very well-preserved impact structure formed on basaltic and subordinately rhyodacites flows of the Serra Geral Formation (about 133-131 Ma), which are locally intertrapped by eolian-sandstones of Botucatu Formation. The impact-related features are represented by shatter cones, breccia-veins and planar deformation features in quartz (few occurrence in the sandstones). This work is focused on the petrogenesis of the centimeter breccia-veins that are found in all lithologies. We conducted a detailed petrological study (petrography, microprobe, SEM, Raman spectroscopy, Spectroscopy of reflectance and XRD) on these veins and their host-rocks. Our results show that the veins were strongly affected by the post-impact hydrothermal fluids. The hydrothermal alteration varies geographically in the structure. On the rim area this alteration consists of total or partial substitution of the melt matrix by quartz, calcite, iron oxides and clay minerals. At the central area, the alteration mineral assembly is composed of quartz, iron oxides, zeolites, clay minerals and rarely calcite. Usually, the alteration shows a zoned setting, which also varies locally. The nature of occurrence of second mineral identified in the context of post-impact hydrothermal alteration of impact craters on basalt represent a critical interpretation to interpret alteration signature of impact craters and the old

  7. Impact of road network on the structure of a multifunctional forest landscape unit in southern Turkey.

    Science.gov (United States)

    Eker, Mehmet; Coban, Huseyin Oguz

    2010-01-01

    Forest roads have many kinds of direct and indirect effects such as physical, ecological, and socio-economic effects in landscape scale. In this study the relationship between forest road network and the structure of a multifunctionally planned forest landscape, in the south of Turkey was examined. The aim of the study was to determine whether or not the correlation between road network and landscape structure across a gradient of road density categorical road/no road approach and landscape pattern data from the managed forest landscapes existed. It was concerned with three type polygons that were forest functioning patches, compartments, and stand patches and were associated with higher road density or existing of road network. To quantify the case, it was analyzed whether the spatial structure of forest patches adjacent to roads differs from the spatial structure of forest patches away from roads. GIS was used to integrate quantitative indices of landscape structure. There was little negatively significant relationship between road density and patch area/size, patch perimeter and shape index of patton index (PI) and no correlation with patch number and Fractal Dimension (FD). The forest road network modified spatial pattern of patch shape through PI values. The road network increased the number of patch and decreased mean patch size. The existence of road network was more effective than topography index appearing of PI and FD in the roaded areas. It was indicated to potential reverse impacts of road network on spatial structure of forest compartments in terms of shape index (FD). Highest proportions of harvestable forest areas fall into roaded areas. The results define that road networks are effective on the spatial structure of forest landscape. The forest road network of study area has all probable ecological impacts of forest roads mentioned in context.

  8. Regulatory Impact of RNA Secondary Structure across the Arabidopsis Transcriptome[W][OA

    Science.gov (United States)

    Li, Fan; Zheng, Qi; Vandivier, Lee E.; Willmann, Matthew R.; Chen, Ying; Gregory, Brian D.

    2012-01-01

    The secondary structure of an RNA molecule plays an integral role in its maturation, regulation, and function. However, the global influence of this feature on plant gene expression is still largely unclear. Here, we use a high-throughput, sequencing-based, structure-mapping approach in conjunction with transcriptome-wide sequencing of rRNA-depleted (RNA sequencing), small RNA, and ribosome-bound RNA populations to investigate the impact of RNA secondary structure on gene expression regulation in Arabidopsis thaliana. From this analysis, we find that highly unpaired and paired RNAs are strongly correlated with euchromatic and heterochromatic epigenetic histone modifications, respectively, providing evidence that secondary structure is necessary for these RNA-mediated posttranscriptional regulatory pathways. Additionally, we uncover key structural patterns across protein-coding transcripts that indicate RNA folding demarcates regions of protein translation and likely affects microRNA-mediated regulation of mRNAs in this model plant. We further reveal that RNA folding is significantly anticorrelated with overall transcript abundance, which is often due to the increased propensity of highly structured mRNAs to be degraded and/or processed into small RNAs. Finally, we find that secondary structure affects mRNA translation, suggesting that this feature regulates plant gene expression at multiple levels. These findings provide a global assessment of RNA folding and its significant regulatory effects in a plant transcriptome. PMID:23150631

  9. Typical structural elements of seismicity and impact crater morphology identified in GIS ENDDB digital models.

    Science.gov (United States)

    Mikheeva, Anna

    2014-05-01

    The subject database of the ENDDB system (Earth's Natural Disasters Database) is a combination of the EISC catalog (Earth's impact structures Catalog [1]) and seismological data of more than 60 earthquake catalogs (EC). ENDDB geographic subsystem uses the NASA ASTER GDEM data arrays to obtain a high-resolution (1 arc-second) shaded relief model, as well as the digital mapping technology, which consists in shading surface points according to their brightness controlled by the illumination angle. For example, the identifying impact craters by means of ENDDB begins with selecting the optimum base colors of the image, the parameters of illumination and shadow depth for constructing a shaded model on a regular grid of values. This procedure allows obtaining precise 3D images of the terrain and gravity patterns, and, moreover, furnishes data for recognizing standard morphological elements according to which impact structures can be visually detected. For constructing a shaded gravity anomaly with the ENDDB tools, Global marine gravity data (of models V16.1 and V18.1 [2]) are embedded into the system. These models, which are arrays of gravity pixel values, are of the resolution increased from the equator to the poles, being 30 arc-seconds per point on average. This resolution is the same as in the more recent V21.1 model. Due to these data, new morphological elements typical of impact structures, which are expressed in the shaded elevation and gravity models (identified using the ENDDB visualization tools) was found and compared in hundreds of craters from the EISC-catalog: tail-shaped asymmetry of relief, heart-shaped geometry of craters, and tail-shaped gravity lows [3] and so on. New diagnostic criteria associated with typical morphological elements revealed with advanced image processing technologies are very important to confirm the impact origin for many potential craters. The basic hypothesis of the impact-explosive tectonics [4] is that meteorite craters on the

  10. Impactites of the Yaxcopoil-1 drilling site, Chicxulub impact structure: Petrography, geochemistry, and depositional environment

    Science.gov (United States)

    Dressler, Burkhard O.; Sharpton, Virgil L.; Schwandt, Craig S.; Ames, Doreen

    2004-01-01

    The impact breccias encountered in drill hole Yaxcopoil-1 (Yax-1) in the Chicxulub impact structure have been subdivided into six units. The two uppermost units are redeposited suevite and suevite, and together are only 28 m thick. The two units below are interpreted as a ground surge deposit similar to a pyroclastic flow in a volcanic regime with a fine-grained top (unit 3; 23 m thick; nuee ardente) and a coarse breccia (unit 4; approx.15 m thick) below. As such, they consist of a melange of clastic matrix breccia and melt breccia. The pyroclastic ground surge deposit and the two units 5 and 6 below are related to the ejecta curtain. Unit 5 (approx.24 m thick) is a silicate impact melt breccia, whereas unit 6 (10 m thick) is largely a carbonate melt breccia with some clastic-matrix components. Unit 5 and 6 reflect an overturning of the target stratigraphy. The suevites of units 1 and 2 were deposited after emplacement of the ejecta curtain debris. Reaction of the super-heated breccias with seawater led to explosive activity similar to phreomagmatic steam explosion in volcanic regimes. This activity caused further brecciation of melt and melt fragments. The fallback suevite deposit of units 1 and 2 is much thinner than suevite deposits at larger distances from the center of the impact structure than the 60 km of the Yax-1 drill site. This is evidence that the fallback suevite deposit (units 1 and 2) originally was much thicker. Unit 1 exhibits sedimentological features suggestive of suevite redeposition. Erosion possibly has occurred right after the IUT impact due to seawater backsurge, but erosion processes spanning thousands of years may also have been active. Therefore, the top of the 100 m thick impactite sequence at Yaxcopoil, in our opinion, is not the K/T boundary.

  11. Origin and emplacement of impactites in the Chesapeake Bay impact structure, Virginia, USA

    Science.gov (United States)

    Horton, J.W.; Gohn, G.S.; Powars, D.S.; Edwards, L.E.

    2007-01-01

    The late Eocene Chesapeake Bay impact structure, located on the Atlantic margin of Virginia, may be Earth's best-preserved large impact structure formed in a shallow marine, siliciclastic, continental-shelf environment. It has the form of an inverted sombrero in which a central crater ???40 km in diameter is surrounded by a shallower brim, the annular trough, that extends the diameter to ???85 km. The annular trough is interpreted to have formed largely by the collapse and mobilization of weak sediments. Crystalline-clast suevite, found only in the central crater, contains clasts and blocks of shocked gneiss that likely were derived from the fragmentation of the central-uplift basement. The suevite and entrained megablocks are interpreted to have formed from impact-melt particles and crystalline-rock debris that never left the central crater, rather than as a fallback deposit. Impact-modified sediments in the annular trough include megablocks of Cretaceous nonmarine sediment disrupted by faults, fluidized sands, fractured clays, and mixed-sediment intercalations. These impact-modified sediments could have formed by a combination of processes, including ejection into and mixing of sediments in the water column, rarefaction-induced fragmentation and clastic injection, liquefaction and fluidization of sand in response to acoustic-wave vibrations, gravitational collapse, and inward lateral spreading. The Exmore beds, which blanket the entire crater and nearby areas, consist of a lower diamicton member overlain by an upper stratified member. They are interpreted as unstratified ocean-resurge deposits, having depositional cycles that may represent stages of inward resurge or outward anti-resurge flow, overlain by stratified fallout of suspended sediment from the water column. ?? 2008 The Geological Society of America. All rights reserved.

  12. Impactites of the Yaxcopoil-1 drilling site, Chicxulub impact structure: Petrography, geochemistry, and depositional environment

    Science.gov (United States)

    Dressler, Burkhard O.; Sharpton, Virgil L.; Schwandt, Craig S.; Ames, Doreen

    2004-01-01

    The impact breccias encountered in drill hole Yaxcopoil-1 (Yax-1) in the Chicxulub impact structure have been subdivided into six units. The two uppermost units are redeposited suevite and suevite, and together are only 28 m thick. The two units below are interpreted as a ground surge deposit similar to a pyroclastic flow in a volcanic regime with a fine-grained top (unit 3; 23 m thick; nuee ardente) and a coarse breccia (unit 4; approx.15 m thick) below. As such, they consist of a melange of clastic matrix breccia and melt breccia. The pyroclastic ground surge deposit and the two units 5 and 6 below are related to the ejecta curtain. Unit 5 (approx.24 m thick) is a silicate impact melt breccia, whereas unit 6 (10 m thick) is largely a carbonate melt breccia with some clastic-matrix components. Unit 5 and 6 reflect an overturning of the target stratigraphy. The suevites of units 1 and 2 were deposited after emplacement of the ejecta curtain debris. Reaction of the super-heated breccias with seawater led to explosive activity similar to phreomagmatic steam explosion in volcanic regimes. This activity caused further brecciation of melt and melt fragments. The fallback suevite deposit of units 1 and 2 is much thinner than suevite deposits at larger distances from the center of the impact structure than the 60 km of the Yax-1 drill site. This is evidence that the fallback suevite deposit (units 1 and 2) originally was much thicker. Unit 1 exhibits sedimentological features suggestive of suevite redeposition. Erosion possibly has occurred right after the IUT impact due to seawater backsurge, but erosion processes spanning thousands of years may also have been active. Therefore, the top of the 100 m thick impactite sequence at Yaxcopoil, in our opinion, is not the K/T boundary.

  13. The impact of structural and functional parameters in glaucoma patients on patient-reported visual functioning.

    Directory of Open Access Journals (Sweden)

    Christoph Hirneiß

    Full Text Available BACKGROUND: To evaluate the impact of structural changes of the retinal nerve fiber layer (RNFL, and visual field loss, on functional impairment assessed by patient-reported visual functioning in glaucoma. METHODS: Patients with glaucomatous optic nerve damage were enrolled in this cross-sectional study. Peripapillary RNFL thickness was obtained with spectral-domain optical coherence tomography (SD-OCT. Function was assessed by patient-reported visual functioning using the Rasch-calibrated Glaucoma Activity Limitation 9 (GAL-9 questionnaire and standard automated perimetry. The impact of peripapillary RNFL loss on functional impairment was analyzed with correlation and linear regression analyses. RESULTS: A total of 176 eyes from 88 glaucoma patients were included. The SD-OCT assessed temporal-superior and temporal-inferior RNFL sector of the worse eye revealed significant correlation with the GAL-9 scores (r=-0.298, p=0.011 and r=-0.251, p=0.033, respectively. In mutivariate regression analysis, the best predictors for patient-reported visual functioning were visual acuity of the better eye and mean defect of the worse eye (R(2=0.334, while structural parameters could not enhance the prediction of GAL-9 scores. CONCLUSIONS: Self-reported visual functioning of patients with glaucoma is better predicted by visual performance data than structural parameters. However, some structural changes of the worse eye are significantly correlated with patient-reported visual functioning.

  14. IMPACT OF URBANIZATION ON STRUCTURE AND FUNCTION OF RIVER SYSTEM--Case Study of Shanghai, China

    Institute of Scientific and Technical Information of China (English)

    YUAN Wen; Philip JAMES; YANG Kai

    2006-01-01

    Urbanization can affect the physical process of river growth, modify stream structure and further influence the functions of river system. Shanghai is one of the largest cities in the world, which is located in Changjiang(Yangtze) River Delta in China. Since the 1970s, the whole river system in Shanghai has been planned and managed by the Shanghai Water Authority. The primary management objectives in the last 30 years have been to enhance irrigation and flood-control. By using Horton-Strahler classification and Horton laws as a reference, a novel method of stream classification, in conjunction with the traditional and specially designed indicators, was applied to understanding the structure and functions of the river system in Shanghai. Correlation analysis was used to identify the interrelations among indicators. It was found that the impact of urbanization on the river system was significant although natural laws and physical characteristics marked a super-developed river system. There was an obvious correlation between the degree of urbanization and the abnormal values of some indicators. Urbanization impacts on river system such as branches engineered out, riverbank concreting and low diversity of river style were widely observed. Each indicator had distinct sensibility to urbanization so they could be used to describe different characteristics of urban river system. The function indicators were significantly related to structure indicators. Stream structure, described by fractal dimension and complexity of river system, was as important as water area ratio for maintaining river's multi-function.

  15. Environmental impact assessment and eco-friendly decision-making in civil structures.

    Science.gov (United States)

    Kim, Sang-Hyo; Choi, Moon-Seock; Mha, Ho-Seong; Joung, Jung-Yeun

    2013-09-15

    This study develops two useful procedures in performing an environmental-impact assessment. One is the advanced life-cycle assessment (LCA) method, which effectively tracks the flow of materials and considers the recycling and demolition of a civil structure. The other is an eco-friendly decision-making procedure, which may effectively apply when determining the prototype of a civil structure. The advanced LCA method differs from traditional LCA procedure, as it classifies the input material prior to the impact assessment. Classification work is performed to establish independent life-cycle stages for each material. The processes of recycling and demolition are appropriately added to the life-cycle stages. The impact assessment is performed separately for the materials, and results are aggregated at the end of the analysis. The eco-friendly decision-making procedure enables designers to choose an economical, and environmentally friendly, alternative during the planning phase of the construction project. This procedure rationally amalgamates economical value and environmental effects into a single indicator. The life cycle cost (LCC) of a structure can be analysed by using conventional LCC tools, whereas the environmental impact is estimated by LCA. The results from LCC and LCA are then integrated by using either a CO2 conversion method or an analytical hierarchy process (AHP). The CO2 conversion method presents the result as a monetary value, whereas the AHP presents the result as a non-dimensional value. A practical example using a steel box girder bridge and a pre-stressed concrete (PSC) box-girder bridge is also given in order to aid the understanding of the presented procedure.

  16. Impact

    NARCIS (Netherlands)

    Lohse, Detlef; Bergmann, Raymond; Mikkelsen, Rene; Zeilstra, Christiaan; Meer, van der Devaraj; Versluis, Michel

    2004-01-01

    A lot of information on impacts of solid bodies on planets has been extracted from remote observations of impact craters on planetary surfaces; experiments however with large enough impact energies as compared to the energy stored in the ground are difficult. We approach this problem by downscaled e

  17. Automated laser-based barely visible impact damage detection in honeycomb sandwich composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Girolamo, D., E-mail: dgirola@ncsu.edu; Yuan, F. G. [National Institute of Aerospace, Integrated Structural Health Management Laboratory, Hampton, VA 23666 and North Carolina State University, Department of Mechanical and Aerospace Engineering, Raleigh, NC 27695 (United States); Girolamo, L. [North Carolina State University, Department of Mechanical and Aerospace Engineering, Raleigh, NC 27695 (United States)

    2015-03-31

    Nondestructive evaluation (NDE) for detection and quantification of damage in composite materials is fundamental in the assessment of the overall structural integrity of modern aerospace systems. Conventional NDE systems have been extensively used to detect the location and size of damages by propagating ultrasonic waves normal to the surface. However they usually require physical contact with the structure and are time consuming and labor intensive. An automated, contactless laser ultrasonic imaging system for barely visible impact damage (BVID) detection in advanced composite structures has been developed to overcome these limitations. Lamb waves are generated by a Q-switched Nd:YAG laser, raster scanned by a set of galvano-mirrors over the damaged area. The out-of-plane vibrations are measured through a laser Doppler Vibrometer (LDV) that is stationary at a point on the corner of the grid. The ultrasonic wave field of the scanned area is reconstructed in polar coordinates and analyzed for high resolution characterization of impact damage in the composite honeycomb panel. Two methodologies are used for ultrasonic wave-field analysis: scattered wave field analysis (SWA) and standing wave energy analysis (SWEA) in the frequency domain. The SWA is employed for processing the wave field and estimate spatially dependent wavenumber values, related to discontinuities in the structural domain. The SWEA algorithm extracts standing waves trapped within damaged areas and, by studying the spectrum of the standing wave field, returns high fidelity damage imaging. While the SWA can be used to locate the impact damage in the honeycomb panel, the SWEA produces damage images in good agreement with X-ray computed tomographic (X-ray CT) scans. The results obtained prove that the laser-based nondestructive system is an effective alternative to overcome limitations of conventional NDI technologies.

  18. Finite Element Simulation of Low Velocity Impact Damage on an Aeronautical Carbon Composite Structure

    Science.gov (United States)

    Lemanle Sanga, Roger Pierre; Garnier, Christian; Pantalé, Olivier

    2016-06-01

    Low velocity barely visible impact damage (BVID) in laminated carbon composite structures has a major importance for aeronautical industries. This contribution leads with the development of finite element models to simulate the initiation and the propagation of internal damage inside a carbon composite structure due by a low velocity impact. Composite plates made from liquid resin infusion process (LRI) have been subjected to low energy impacts (around 25 J) using a drop weight machine. In the experimental procedure, the internal damage is evaluated using an infrared thermographic camera while the indentation depth of the face is measured by optical measurement technique. In a first time we developed a robust model using homogenised shells based on degenerated tri-dimensional brick elements and in a second time we decided to modelize the whole stacking sequence of homogeneous layers and cohesive interlaminar interfaces in order to compare and validate the obtained results. Both layer and interface damage initiation and propagation models based on the Hashin and the Benzeggagh-Kenane criteria have been used for the numerical simulations. Comparison of numerical results and experiments has shown the accuracy of the proposed models.

  19. Digital image analysis of ASB-assisted failure of impacted structural materials

    Directory of Open Access Journals (Sweden)

    Longère Patrice

    2015-01-01

    Full Text Available Experimental analysis of fracture mechanisms is a key point to understand and further reproduce physical phenomena involved in structural material failure. Actually, crack propagation under high loading rate is a strongly coupled thermo-mechanical problem involving large deformation, high strain rate and (quasi adiabatic conditions. The work presented herein aims at analyzing the successive steps of the dynamic deterioration of a high strength structural material, namely the ARMOX500T armor steel, leading to the ultimate fracture. The Kalthoff and Winkler impact test, consisting in impacting the edge of a double notched plate, was retained for that purpose. Images are captured at high frame rate (1M frame/s during the impact loading then analyzed according to a line tracking method. Three stages are accordingly observed: first the progressive development of a weak localization of the deformation within a wide zone behind the notch tips, second the propagation of a narrow band of strong localization, and finally the propagation of a crack. The propagation of the white band is associated to the development of an adiabatic shear band (ASB, as a precursor of the crack. Corresponding displacement fields are identified thanks to the adopted line tracking method, allowing for determining the evolution of mechanical quantities, including notably notch tip shear displacement and velocity, ASB-related white band velocity, global and local shear strain and shear strain rate magnitudes, in view of being implemented into numerical models.

  20. Torsion Property of the Structure Bonded Aluminum Foam Due to Impact

    Directory of Open Access Journals (Sweden)

    Hwang G.W.

    2017-06-01

    Full Text Available An aluminum foam added with foaming agent, is classified into an open-cell type for heat transfer and a closed-cell type for shock absorption. This study investigates the characteristic on the torsion of aluminum foam for a closed-cell type under impact. The fracture characteristics are investigated through the composite of five types of aluminum foam (the thicknesses of 25, 35, 45, 55 and 65 mm, when applying the torsional moment of impact energy on the junction of a porous structure attached by an adhesive. When applying the impact energy of 100, 200 and 300J, the aluminum foams with thicknesses of 25 mm and 35 mm broke off under all conditions. For the energy over 200J, aluminums thicker than 55 mm continued to be attached. Furthermore, the aluminum specimens with thicknesses of 55 mm and 65 mm that were attached with more than 30% of bonding interface remained, proving that they could maintain bonding interface against impact energy. By comparing the data based on the analysis and test result, an increase in the thickness of specimen leads to the plastic deformation as the stress at the top and bottom of bonding interface moves to the middle by spreading the stress horizontally. Based on this fracture characteristic, this study can provide the data on the destruction and separation of bonding interface and may contribute to the safety design.

  1. Fully Nonlinear Simulation for Fluid/Structure Impact:A Review

    Institute of Scientific and Technical Information of China (English)

    Shili Sun; Guoxiong Wu

    2014-01-01

    This paper presents a review of the work on fluid/structure impact based on inviscid and imcompressible liquid and irrotational flow. The focus is on the velocity potential theory together with boundary element method (BEM). Fully nonlinear boundary conditions are imposed on the unknown free surface and the wetted surface of the moving body. The review includes (1) vertical and oblique water entry of a body at constant or a prescribed varying speed, as well as free fall motion, (2) liquid droplets or column impact as well as wave impact on a body, (3) similarity solution of an expanding body. It covers two dimensional (2D), axisymmetric and three dimensional (3D) cases. Key techniques used in the numerical simulation are outlined, including mesh generation on the multivalued free surface, the stretched coordinate system for expanding domain, the auxiliary function method for decoupling the mutual dependence of the pressure and the body motion, and treatment for the jet or the thin liquid film developed during impact.

  2. The Impact of EU Structural Fund Support and Problems of its Absorption

    Directory of Open Access Journals (Sweden)

    Daiva Jurevičienė

    2013-06-01

    Full Text Available Targeted allocation of EU support in Lithuania can help resolving a number of problems and achieving significant results in a variety of areas. However, rush to absorb support may lead to a little, zero or even negative impact on national economy. In addition, EU support opportunities may distort investment motivation. This paper deals with issues related to the impact of EU support and problems of its absorption. The impact of EU support on the national economy has been established in three areas: attraction of foreign direct investment state investments into capital formation, and experience of companies, which are EU support beneficiaries. The paper proposes using regression analysis in search and evaluation of relations while obtaining more information about programmes, priorities and the impact of structural support on different indicators. In addition, it focuses on ascertaining the effectiveness of governmental and company spending. Furthermore, as companies – EU support beneficiaries – are engaged in different economic activities, their experience cannot be ascertained from statistical data; consequently, findings of an expert survey are presented to demonstrate the experience acquired by business companies as well as problems they face. Limitation of research was a short period of time to evaluate (only four years of the current funding period

  3. Embryo impacts and gas giant mergers - II. Diversity of hot Jupiters' internal structure

    Science.gov (United States)

    Liu, Shang-Fei; Agnor, Craig B.; Lin, D. N. C.; Li, Shu-Lin

    2015-01-01

    We consider the origin of compact, short-period, Jupiter-mass planets. We propose that their diverse structure is caused by giant impacts of embryos and super-Earths or mergers with other gas giants during the formation and evolution of these hot Jupiters. Through a series of numerical simulations, we show that typical head-on collisions generally lead to total coalescence of impinging gas giants. Although extremely energetic collisions can disintegrate the envelope of gas giants, these events seldom occur. During oblique and moderately energetic collisions, the merger products retain higher fraction of the colliders' cores than their envelopes. They can also deposit considerable amount of spin angular momentum to the gas giants and desynchronize their spins from their orbital mean motion. We find that the oblateness of gas giants can be used to infer the impact history. Subsequent dissipation of stellar tide inside the planets' envelope can lead to runaway inflation and potentially a substantial loss of gas through Roche lobe overflow. The impact of super-Earths on parabolic orbits can also enlarge gas giant planets' envelope and elevates their tidal dissipation rate over ˜100 Myr time scale. Since giant impacts occur stochastically with a range of impactor sizes and energies, their diverse outcomes may account for the dispersion in the mass-radius relationship of hot Jupiters.

  4. The impact structure of social capital on corporate performance: Empirical evidence from listed companies in China

    Institute of Scientific and Technical Information of China (English)

    SHI Junwei; FU Haiyan; HU Lijun

    2007-01-01

    Vertical relationships with the government, particular relational capital and organizational social network capital, constitute corporate social capital (CSC). Using the empirical data of 97 listed companies in China, this paper examines the impact of CSC on corporate performance, finds that CSC has a positive impact on sales revenue but an insignificant impact on the improvement of ROA. More specifically, when a firm enlarges its sales revenue, the function of organizational network capital is stronger than that of a particular relational capital and that of governmental connections. The paper also finds that state-owned enterprises (SOEs) have more advantages in using governmental connections, therefore leading to better social status than non-SOEs do, who have fewer advantages in using any particular relational capital. The article suggests that managers should appraise carefully the effectiveness of CSC, and combine it with other resources; firms should distinguish the structure of the impact of CSC on performance improvement in a dynamic way. With respect to the implication of this paper, it could help in analyzing firm behaviors in the transitional China.

  5. Effects of reinforcement ratio and arrangement on the structural behavior of a nuclear building under aircraft impact

    Energy Technology Data Exchange (ETDEWEB)

    Thai, Duc-Kien; Kim, Seung-Eock, E-mail: sekim@sejong.ac.kr; Lee, Hyuk-Kee

    2014-09-15

    Highlights: • Numerical analysis of RC nuclear building model under aircraft impact was conducted. • The analysis result shows similar behavior as compared to the Riera function. • The effects of reinforcement ratio and arrangement were enumerated. • The appropriate number of layer of longitudinal rebar was recommended. - Abstract: This study presents the effectiveness of the rebar ratio and the arrangement of reinforced concrete (RC) structures on the structural behavior of nuclear buildings under aircraft impact using a finite element (FE) approach. A simplified model of a fictitious nuclear building using RC structures was fully modeled. The aircraft model of a Boeing 767-400 was used for impact simulation and was developed and verified with a conventional impact force–time history curve. The IRIS Punching test was used to validate the damage prediction capabilities of the RC wall under impact loading. With regard to the different rebar ratios and rebar arrangements of a nuclear RC building, the structural behavior of a building under aircraft impact was investigated. The structural behavior investigated included plastic deformation, displacement, energy dissipation, perforation/penetration depth and scabbing area. The results showed that the rebar ratio has a significant effect on withstanding aircraft impact and reducing local damage. With four layers of rebar, the RC wall absorbed and dissipated the impact energy more than once with only two layers of rebar for the same rebar ratio.

  6. The Surface of Venus is Saturated With Ancient Impact Structures, and its Plains are Marine Sediments

    Science.gov (United States)

    Hamilton, W. B.

    2009-05-01

    Conventional interpretations of Venus are forced to fit dubious pre-Magellan conjectures that the planet is as active internally as Earth and preserves no ancient surface features. Plate tectonics obviously does not operate, so it is commonly assumed that the surface must record other endogenic processes, mostly unique to Venus. Imaginative systems of hundreds of tiny to huge rising and sinking plumes and diapirs are invoked. That much of the surface in fact is saturated with overlapping large circular depressions with the morphology of impact structures is obscured by postulating plume origins for selected structures and disregarding the rest. Typical structures are rimmed circular depressions, often multiring, with lobate debris aprons; central peaks are common. Marine-sedimentation features are overlooked because dogma deems the plains to be basalt flows despite their lack of source volcanoes and fissures. The unearthly close correlation between geoid and topography at long to moderate wavelengths requires, in conventional terms, dynamic maintenance of topography by up and down plumes of long-sustained precise shapes and buoyancy. A venusian upper mantle much stronger than that of Earth, because it is cooler or poorer in volatiles, is not considered. (The unearthly large so-called volcanoes and tessera plateaus often are related to rimmed circular depressions and likely are products of impact fluidization and melting.) Plains-saturating impact structures (mostly more obvious in altimetry than backscatter) with diameters of hundreds of km are superimposed as cookie-cutter bites, are variably smoothed and smeared by apparent submarine impact and erosion, and are differentially buried by sediments compacted into them. Marine- sedimentation evidence includes this compaction; long sinuous channels and distributaries with turbidite- channel characteristics and turbidite-like lobate flows (Jones and Pickering, JGSL 2003); radar-smooth surfaces and laminated aspect in

  7. Breaking wave impact forces on truss support structures for offshore wind turbines

    Science.gov (United States)

    Cieślikiewicz, Witold; Gudmestad, Ove T.; Podrażka, Olga

    2014-05-01

    Due to depletion of the conventional energy sources, wind energy is becoming more popular these days. Wind energy is being produced mostly from onshore farms, but there is a clear tendency to transfer wind farms to the sea. The foundations of offshore wind turbines may be truss structures and might be located in shallow water, where are subjected to highly varying hydrodynamic loads, particularly from plunging breaking waves. There are models for impact forces prediction on monopiles. Typically the total wave force on slender pile from breaking waves is a superposition of slowly varying quasi-static force, calculated from the Morison equation and additional dynamical, short duration force due to the impact of the breaker front or breaker tongue. There is not much research done on the truss structures of wind turbines and there are still uncertainties on slamming wave forces, due to plunging breaking waves on those structures. Within the WaveSlam (Wave slamming forces on truss structures in shallow water) project the large scale tests were carried out in 2013 at the Large Wave Flume in Forschungszentrum Küste (FZK) in Hannover, Germany. The following institutions participated in this initiative: the University of Stavanger and the Norwegian University of Science and Technology (project management), University of Gdańsk, Poland, Hamburg University of Technology and the University of Rostock, Germany and Reinertsen AS, Norway. This work was supported by the EU 7th Framework Programme through the grant to the budget of the Integrating Activity HYDRALAB IV. The main aim of the experiment was to investigate the wave slamming forces on truss structures, development of new and improvement of existing methods to calculate forces from the plunging breakers. The majority of the measurements were carried out for regular waves with specified frequencies and wave heights as well as for the irregular waves based on JONSWAP spectrum. The truss structure was equipped with both

  8. Impact of Hydrotechnical Structures on Hydrological Regime of the Gwda and Drawa Rivers

    Directory of Open Access Journals (Sweden)

    Kubiak-Wójcicka Katarzyna

    2015-03-01

    Full Text Available The work attempts to determine the impact of hydrotechnical structures on regimes of rivers. The aim of the article is to compare hydrological regimes of the rivers Gwda and Drawa due to the differences of hydrotechnical works located on both rivers. The Gwda River is heavily managed by hydrotechnical infrastructure. Presently, there are twelve hydropower plants located along the entire length of the river. The Drawa River, on the other hand, has little hydrotechnical infrastructure. Only two hydropower plants are located on the Drawa River. The study of the hydrological regime was carried out on the basis of the analysis of changes of water stages and ice phenomena. River profiles selected for the analysis were located downstream of hydrotechnical works, i.e. hydropower plants. The conclusions were based on the comparative analysis. The impacts were identified as the differences in processes described by the analyzed parameters

  9. Distribution of siderophile and other trace elements in melt rock at the Chicxulub impact structure

    Science.gov (United States)

    Schuraytz, B. C.; Lindstrom, D. J.; Martinez, R. R.; Sharpton, V. L.; Marin, L. E.

    1994-01-01

    Recent isotopic and mineralogical studies have demonstrated a temporal and chemical link between the Chicxulub multiring impact basin and ejecta at the Cretaceous-Tertiary boundary. A fundamental problem yet to be resolved, however, is identification of the projectile responsible for this cataclysmic event. Drill core samples of impact melt rock from the Chichxulub structure contain Ir and Os abundances and Re-Os isotopic ratios indicating the presence of up to approx. 3 percent meteoritic material. We have used a technique involving microdrilling and high sensitivity instrumental neutron activation analysis (INAA) in conjunction with electron microprobe analysis to characterize further the distribution of siderophile and other trace elements among phases within the C1-N10 melt rock.

  10. Evidence for a meteoritic component in impact melt rock from the Chicxulub structure

    Science.gov (United States)

    Koeberl, Christian; Sharpton, Virgil L.; Schuraytz, Benjamin C.; Shirey, Steven B.; Blum, Joel D.; Marin, Luis E.; Koeberl, Christian

    1994-03-01

    The Chicxulub structure in Yucatan, Mexico, has recently been recognized as a greater than 200-km diameter multi-ring impact crater of K-T boundary age. Crystalline impact melt rocks and breccias from within the crater, which have compositions similar to those of normal continental crustal rocks and which show shock metamorphic effects, have been studied for trace element and Re-Os isotope compositions. A melt rock sample shows elevated iridium concentrations, an osmium concentration of 25 ppb, and a low Os-187/Os-188 ratio of 0.113, which are incompatible with derivation from the continental crust. Even though the Os-187/Os-188 ratio is slightly lower than the range so far measured in meteorites, a mantle origin seems unlikely for mass balance reasons and because the cratering event is unlikely to have excavated mantle material. The data support the hypothesis of a heterogeneously distributed meteoritic component in the Chicxulub melt rock.

  11. Embryo impacts and gas giant mergers II: Diversity of Hot Jupiters' internal structure

    CERN Document Server

    Liu, Shang-Fei; Lin, D N C; Li, Shu-Lin

    2014-01-01

    We consider the origin of compact, short-period, Jupiter-mass planets. We propose that their diverse structure is caused by giant impacts of embryos and super-Earths or mergers with other gas giants during the formation and evolution of these hot Jupiters. Through a series of numerical simulations, we show that typical head-on collisions generally lead to total coalescence of impinging gas giants. Although extremely energetic collisions can disintegrate the envelope of gas giants, these events seldom occur. During oblique and moderately energetic collisions, the merger products retain higher fraction of the colliders' cores than their envelopes. They can also deposit considerable amount of spin angular momentum to the gas giants and desynchronize their spins from their orbital mean motion. We find that the oblateness of gas giants can be used to infer the impact history. Subsequent dissipation of stellar tide inside the planets' envelope can lead to runaway inflation and potentially a substantial loss of gas ...

  12. Thermal annealing of carbon nanotubes reveals a toxicological impact of the structural defects

    Energy Technology Data Exchange (ETDEWEB)

    Figarol, Agathe, E-mail: figarol@emse.fr [Ecole Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR 5307, LGF (France); Pourchez, Jérémie, E-mail: pourchez@emse.fr [Ecole Nationale Supérieure des Mines, CIS-EMSE, EA 4624, SFR IFRESIS, LINA (France); Boudard, Delphine [Université Jean Monnet Saint-Etienne, EA 4624, SFR IFRESIS, LINA (France); Forest, Valérie [Ecole Nationale Supérieure des Mines, CIS-EMSE, EA 4624, SFR IFRESIS, LINA (France); Berhanu, Sarah [Armines - Mines ParisTech, Centre des Matériaux, CNRS UMR 7633 (France); Tulliani, Jean-Marc [Politecnico di Torino, Department of Applied Science and Technology (Italy); Lecompte, Jean-Pierre [Centre Européen de la céramique CNRS: UMR 7315, SPCTS (France); Cottier, Michèle [Université Jean Monnet Saint-Etienne, EA 4624, SFR IFRESIS, LINA (France); Bernache-Assollant, Didier [Ecole Nationale Supérieure des Mines, CIS-EMSE, EA 4624, SFR IFRESIS, LINA (France); Grosseau, Philippe [Ecole Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR 5307, LGF (France)

    2015-04-15

    The biological response to pristine and annealed multi-walled carbon nanotubes (MWCNT) was assessed on murine macrophages (RAW 264.7). First, the physicochemical features of the as-produced MWCNT and annealed at 2125 °C for 1 h were fully characterized. A decrease in structural defects, hydrophobicity and catalytic impurities was detected after annealing. Thereafter, their impact on cytotoxicity, oxidative stress, and pro-inflammatory response was investigated at concentrations ranging from 15 to 120 µg mL{sup −1}. No effect of the 2125 °C treatment was detected on the cytotoxicity. In contrast, the annealed carbon nanotubes showed a significant increase of the pro-inflammatory response. We assumed that this behavior was due to the reduction in structural defects that may modify the layer of adsorbed biomolecules. Surprisingly, the purification of metallic catalysts did not have any significant impact on the oxidative stress. We suggested that the structural improvements from the 2125 °C treatment can decrease the carbon nanotube scavenging capacity and thus allow a higher free radical release which may counterbalance the decrease of oxidative stress due to a lower content of metallic impurities.

  13. Analysis of opinion spreading in signed social networks under the impact of structural balance

    Science.gov (United States)

    Li, Pei; Zhang, Yini; He, Su; Wang, Hui

    2015-03-01

    Social networks have attracted remarkable attention and it is of great importance to understand the process of opinion spreading in popular social networks. However, most research on diffusion cannot be applied directly to investigate social networks, where relationships are heterogeneous and structural balance is a common phenomenon. In this paper, we propose models to characterize the process of opinion spreading in signed social networks under the impact of structural balance. We classify users into different types according to the numbers of their positive links, and define the term user influence to represent the average number of times that users are influenced, which is incurred by a user spreading an opinion. We then propose an approach to analyze the user influence theoretically and the analysis accuracy is verified by simulations. We observe that the user influence increases with user type and also increases with the fraction of negative links in the network if this fraction value exceeds some point. That's to say, negative relationships may enhance opinion spreading if we consider the impact of structural balance, which is an interesting result.

  14. The impact of deregulation on the board structure of electric utilities

    Science.gov (United States)

    Wollan, Patricia L.

    This study analyzes the impact of deregulation on board structure by comparing the boards of electric utilities before and after the passage of the Energy Policy Act (EPACT). In addition, the study assesses whether board structure has an impact on firm performance during the period of transition. I find that electric utilities do change their board structure in response to their new operating environment. Boards are smaller and more independent in the later period. Also, even though the number of outside directors stays the same, there are notable changes in the character of these directors. The number of executives from large firms and the number of directors with political backgrounds are both significantly greater after the passage of EPACT. These results are consistent with Williamson's hypothesis that firms will change the composition and character of their board in response to a change in the firm's operating environment. Further investigation reveals that even though utilities' boards change following deregulation, the pace of change is slow, and during the four-year period immediately following the passage of EPACT firm performance is related to board character. These results suggest that while firms reconfigure their boards in response to a change in their operating environment, there may be impediments that prevent them from adjusting their boards too quickly.

  15. Rate Dependent Multicontinuum Progressive Failure Analysis of Woven Fabric Composite Structures under Dynamic Impact

    Directory of Open Access Journals (Sweden)

    James Lua

    2004-01-01

    Full Text Available Marine composite materials typically exhibit significant rate dependent response characteristics when subjected to extreme dynamic loading conditions. In this work, a strain-rate dependent continuum damage model is incorporated with multicontinuum technology (MCT to predict damage and failure progression for composite material structures. MCT treats the constituents of a woven fabric composite as separate but linked continua, thereby allowing a designer to extract constituent stress/strain information in a structural analysis. The MCT algorithm and material damage model are numerically implemented with the explicit finite element code LS-DYNA3D via a user-defined material model (umat. The effects of the strain-rate hardening model are demonstrated through both simple single element analyses for woven fabric composites and also structural level impact simulations of a composite panel subjected to various impact conditions. Progressive damage at the constituent level is monitored throughout the loading. The results qualitatively illustrate the value of rate dependent material models for marine composite materials under extreme dynamic loading conditions.

  16. A marine magnetic study of a carbonate-hosted impact structure: Ile Rouleau, Canada

    Science.gov (United States)

    Evangelatos, John; Butler, Karl E.; Spray, John G.

    2009-10-01

    Marine magnetic and bathymetric data have been acquired in a 6.5 × 10 km area centred on the Ile Rouleau impact structure, Quebec, Canada. The deeply eroded crater is emplaced in weakly magnetic shaley dolomites of the Palaeoproterozoic Mistassini Group. Subaerial exposure of the structure consists of an island (Ile Mintunikus Misaupinanuch) in Lac Mistassini, which hosts shatter cones. Short-wavelength and linear NNE-trending magnetic anomalies that pervade the survey area are inferred to reflect the presence of magnetic glacial landforms on the lake floor. The most prominent magnetic feature is a high-amplitude anomaly that wraps round the western side of the island. The anomaly correlates with an abrupt change in bathymetry but is not consistently circular about the island and its relationship to the impact is unclear. To the east, a disjointed arcuate anomaly lies parallel to the island 100 m from shore. Its source may be interpreted to be either (1) a locally thickened layer of magnetic glaciofluvial deposits, or (2) post-impact chemically induced magnetization along faults. The abrupt variations in glaciofluvial thickness needed to account for the anomaly under scenario (1) are, however, hard to explain geologically and hypothesis (2) is therefore favoured. Regardless of which model is correct, both suggest that the arcuate anomaly coincides with the fault-bounded perimeter of a central peak. Two possible reconstructions for the original crater diameter, estimated from the curvature of the magnetic anomaly and using morphometric relationships, are 4.4 km and 6.8 km. The former is more realistic with regards to the topography and the lack of conspicuous impact-related deformation on adjacent Ile Manitounouc.

  17. The Impact of Youth-Friendly Structures of Care on Retention Among HIV-Infected Youth.

    Science.gov (United States)

    Lee, Lana; Yehia, Baligh R; Gaur, Aditya H; Rutstein, Richard; Gebo, Kelly; Keruly, Jeanne C; Moore, Richard D; Nijhawan, Ank E; Agwu, Allison L

    2016-04-01

    Limited data exist on how structures of care impact retention among youth living with HIV (YLHIV). We describe the availability of youth-friendly structures of care within HIV Research Network (HIVRN) clinics and examine their association with retention in HIV care. Data from 680 15- to 24-year-old YLHIV receiving care at 7 adult and 5 pediatric clinics in 2011 were included in the analysis. The primary outcome was retention in care, defined as completing ≥2 primary HIV care visits ≥90 days apart in a 12-month period. Sites were surveyed to assess the availability of clinic structures defined a priori as 'youth-friendly'. Univariate and multivariable logistic regression models assessed structures associated with retention in care. Among 680 YLHIV, 85% were retained. Nearly half (48%) of the 680 YLHIV attended clinics with youth-friendly waiting areas, 36% attended clinics with evening hours, 73% attended clinics with adolescent health-trained providers, 87% could email or text message providers, and 73% could schedule a routine appointment within 2 weeks. Adjusting for demographic and clinical factors, YLHIV were more likely to be retained in care at clinics with a youth-friendly waiting area (AOR 2.47, 95% CI [1.11-5.52]), evening clinic hours (AOR 1.94; 95% CI [1.13-3.33]), and providers with adolescent health training (AOR 1.98; 95% CI [1.01-3.86]). Youth-friendly structures of care impact retention in care among YLHIV. Further investigations are needed to determine how to effectively implement youth-friendly strategies across clinical settings where YLHIV receive care.

  18. A single frequency component-based re-estimated MUSIC algorithm for impact localization on complex composite structures

    Science.gov (United States)

    Yuan, Shenfang; Bao, Qiao; Qiu, Lei; Zhong, Yongteng

    2015-10-01

    The growing use of composite materials on aircraft structures has attracted much attention for impact monitoring as a kind of structural health monitoring (SHM) method. Multiple signal classification (MUSIC)-based monitoring technology is a promising method because of its directional scanning ability and easy arrangement of the sensor array. However, for applications on real complex structures, some challenges still exist. The impact-induced elastic waves usually exhibit a wide-band performance, giving rise to the difficulty in obtaining the phase velocity directly. In addition, composite structures usually have obvious anisotropy, and the complex structural style of real aircrafts further enhances this performance, which greatly reduces the localization precision of the MUSIC-based method. To improve the MUSIC-based impact monitoring method, this paper first analyzes and demonstrates the influence of measurement precision of the phase velocity on the localization results of the MUSIC impact localization method. In order to improve the accuracy of the phase velocity measurement, a single frequency component extraction method is presented. Additionally, a single frequency component-based re-estimated MUSIC (SFCBR-MUSIC) algorithm is proposed to reduce the localization error caused by the anisotropy of the complex composite structure. The proposed method is verified on a real composite aircraft wing box, which has T-stiffeners and screw holes. Three typical categories of 41 impacts are monitored. Experimental results show that the SFCBR-MUSIC algorithm can localize impact on complex composite structures with an obviously improved accuracy.

  19. The impact of large scale ionospheric structure on radio occultation retrievals

    Directory of Open Access Journals (Sweden)

    A. J. Mannucci

    2011-12-01

    Full Text Available We study the impact of large-scale ionospheric structure on the accuracy of radio occultation (RO retrievals. We use a climatological model of the ionosphere as well as an ionospheric data assimilation model to compare quiet and geomagnetically disturbed conditions. The presence of ionospheric electron density gradients during disturbed conditions increases the physical separation of the two GPS frequencies as the GPS signal traverses the ionosphere and atmosphere. We analyze this effect in detail using ray-tracing and a full geophysical retrieval system. During quiet conditions, our results are similar to previously published studies. The impact of a major ionospheric storm is analyzed using data from the 30 October 2003 "Halloween" superstorm period. At 40 km altitude, the refractivity bias under disturbed conditions is approximately three times larger than quiet time. These results suggest the need for ionospheric monitoring as part of an RO-based climate observation strategy. We find that even during quiet conditions, the magnitude of retrieval bias depends critically on assumed ionospheric electron density structure, which may explain variations in previously published bias estimates that use a variety of assumptions regarding large scale ionospheric structure. We quantify the impact of spacecraft orbit altitude on the magnitude of bending angle and retrieval error. Satellites in higher altitude orbits (700+ km tend to have lower residual biases due to the tendency of the residual bending to cancel between the top and bottomside ionosphere. Another factor affecting accuracy is the commonly-used assumption that refractive index is unity at the receiver. We conclude with remarks on the implications of this study for long-term climate monitoring using RO.

  20. Anatomy of the Chesapeake Bay impact structure revealed by seismic imaging, Delmarva Peninsula, Virginia, USA

    Science.gov (United States)

    Catchings, R.D.; Powars, D.S.; Gohn, G.S.; Horton, J.W.; Goldman, M.R.; Hole, J.A.

    2008-01-01

    A 30-km-long, radial seismic reflection and refraction survey completed across the northern part of the late Eocene Chesapeake Bay impact structure (CBIS) on the Delmarva Peninsula, Virginia, USA, confirms that the CBIS is a complex central-peak crater. We used a tomographic P wave velocity model and low-fold reflection images, constrained by data from two deep boreholes located on the profile, to interpret the structure and composition of the upper 5 km of crust. The seismic images exhibit well-defined structural features, including (with increasing radial distance) a collapsed central uplift, a breccia-filled moat, and a collapsed transient-crater margin (which collectively constitute a ???40-km-wide collapsed transient crater), and a shallowly deformed annular trough. These seismic images are the first to resolve the deep structure of the crater (>1 km) and the boundaries between the central uplift, moat, and annular trough. Several distinct seismic signatures distinguish breccia units from each other and from more coherent crystalline rocks below the central uplift, moat, and annular trough. Within the moat, breccia extends to a minimum depth of 1.5 km or a maximum of 3.5 km, depending upon the interpretation of the deepest layered materials. The images show ???350 to 500 m of postimpact sediments above the impactites. The imaged structure of the CBIS indicates a complex sequence of event during the cratering process that will provide new constraints for numerical modeling. Copyright 2008 by the American Geophysical Union.

  1. Impacts of Vertical Structure of Convection on Tropical Circulation in a Warmer Climate

    Science.gov (United States)

    Chen, C. A.; Chou, C.

    2014-12-01

    The atmosphere becomes warmer and more humid under global warming, while changes in precipitation show a large discrepancy on a regional scale. Changes in regional precipitation are usually associated with changes in tropical circulation. Stronger (weaker) upward motion enhances (reduces) precipitation amount and intensity, in addition to the effect of enhanced water vapor. In a more detailed analysis, however, changes in atmospheric vertical motion can be either strengthened or weakened, even within convective areas with positive rainfall anomalies. To understand the diverse responses of changes in tropical circulation in a warmer climate as well as the associated mechanism, atmospheric stability and the impact of the vertical structure of convection on tropical circulation are investigated in 32 coupled global climate models from CMIP3 and CMIP5. The study regions are convective areas with positive precipitation anomalies. Under global warming, an upward shift structure of vertical velocity is observed in all model simulations, which implies a deepening of convection and a more stable atmosphere. Areas with enhanced (weakened) ascending motion, the climatological bottom-heavy (top-heavy) structure of vertical velocity tends to import more (less) moist static energy to counteract the stabilization due to the effect of deepened convection, and then the ascending motion is strengthened (weakened). The bottom-heavy-like structure is dominated by shallow convection, while the top-heavy-like structure is usually associated with deep convection. In other words, shallow convection tends to strengthen tropical circulation and enhance upward motion in future climate.

  2. Spike Train Auto-Structure Impacts Post-Synaptic Firing and Timing-Based Plasticity

    Science.gov (United States)

    Scheller, Bertram; Castellano, Marta; Vicente, Raul; Pipa, Gordon

    2011-01-01

    Cortical neurons are typically driven by several thousand synapses. The precise spatiotemporal pattern formed by these inputs can modulate the response of a post-synaptic cell. In this work, we explore how the temporal structure of pre-synaptic inhibitory and excitatory inputs impact the post-synaptic firing of a conductance-based integrate and fire neuron. Both the excitatory and inhibitory input was modeled by renewal gamma processes with varying shape factors for modeling regular and temporally random Poisson activity. We demonstrate that the temporal structure of mutually independent inputs affects the post-synaptic firing, while the strength of the effect depends on the firing rates of both the excitatory and inhibitory inputs. In a second step, we explore the effect of temporal structure of mutually independent inputs on a simple version of Hebbian learning, i.e., hard bound spike-timing-dependent plasticity. We explore both the equilibrium weight distribution and the speed of the transient weight dynamics for different mutually independent gamma processes. We find that both the equilibrium distribution of the synaptic weights and the speed of synaptic changes are modulated by the temporal structure of the input. Finally, we highlight that the sensitivity of both the post-synaptic firing as well as the spike-timing-dependent plasticity on the auto-structure of the input of a neuron could be used to modulate the learning rate of synaptic modification. PMID:22203800

  3. Simplified Dynamic Structural Time History Response Analysis of Flexible Approach Walls Founded on Clustered Pile Groups Using Impact_Deck

    Science.gov (United States)

    2016-07-01

    The user assigns a fixed ERDC/ITL TR-16-1 243 damping ratio and Impact_Deck estimates the natural frequencies and calculate the coefficients...for a similar structure. ERDC/ITL TR-16-1 244 I.4 Flexible Wall frequency estimates For the flexible wall problem specified in Appendix C...Impact_Deck example problem . .......................... 39 Table 2.4 Extreme forces/moments for the Impact_Deck example problem

  4. Impact of predation by Ostracion immaculatus (Pisces: Ostraciidae) on the macrofouling community structure in Kanayama Bay, Kii Peninsula (Japan)

    Digital Repository Service at National Institute of Oceanography (India)

    Raveendran, T.V.; Harada, E.

    An investigation on the impact of predation by Ostracion immaculatus on fouling community structure in Kanayama Bay, Kii Peninsula, Japan was undertaken from April 1994 to February 1995. Caging experiments with three size groups of O. immaculatus...

  5. Trace Element Geochemistry of Matrix Glass from the Bedout Impact Structure,Canning Basin NW Australia

    Science.gov (United States)

    Poreda, R. J.; Basu, A. R.; Chakrabarti, R.; Becker, L.

    2004-12-01

    We report on geochemical and petrographic analysis of separated matrix glass from Lagrange-1 and Bedout-1 drill cores that penetrated the Bedout structure offshore NW Australia. The results support the conclusion that the Bedout structure was produced by a a major ET impact at the end-Permian that generated shock melted glass and impact breccias (Becker et al., Science, v.304, p.1469, 2004) The Bedout structure is a 30 km, circular, 1.5 km uplifted basment high that occurs on the passive margin offshore NW Australia. The isolated feature, covered by 3 km of Triassic to Recent sediments,is not consistent with any typical volcanic province (i.e. arc or hotspot volcanism). This hypothesis is supported by the unique mineralogy and chemistry of the matrix glass. At Lagrange, major elements crudely resemble low-K, Fe-Ti basalts while the trace element patterns have two distinct signatures. The lower 250 m of Lagrange (3260 - 3010 m depth) have essentially flat REE and "spider" patterns that superficially resemble some E-MORB; a signal not typically found in arc, hotspot or continental margin settings. The upper 150 meters (3000 - 2850m) of Lagrange and the entire Bedout core (3030 - 3070m) have similar light REE-enriched patterns but low levels of alkalis, alkaline-earths and high field strength elements. Again, the chemistry is not consistent with an arc or hotspot setting, based on the low Ba and extremely low Sr (30-110 ppm) concentrations. Based on the geophysical, chemical and petrologic evidence, we hypothesize that the Bedout structure formed as the result` of an ET impact with Permian age rift margin basalts and continental sediment. The basalts did not completely melt as evidenced by the abundance of large (1 mm) An50 plagioclase,that exist as both crystalline plag and shock melted maskelynite. Plagioclase is the major repository of Sr in basalts and the lack of a plagioclase contribution to the melt glass is reflected in the low Sr abundance. Shock

  6. Fragment structure from vapor explosions during the impact of molten metal droplets into a liquid pool

    Science.gov (United States)

    Kouraytem, Nadia; Li, Er Qiang; Vakarelski, Ivan Uriev; Thoroddsen, Sigurdur

    2015-11-01

    High-speed video imaging is used in order to look at the impact of a molten metal drop falling into a liquid pool. The interaction regimes are three: film boiling, nucleate boiling or vapor explosion. Following the vapor explosion, the metal fragments and different textures are observed. It was seen that, using a tin alloy, a porous structure results whereas using a distinctive eutectic metal, Field's metal, micro beads are formed. Different parameters such as the metal type, molten metal temperature, pool surface tension and pool boiling temperature have been altered in order to assess the role they play on the explosion dynamics and the molten metal's by product.

  7. Impacts of Seed Dispersal on Future Vegetation Structure under Changing Climates

    Science.gov (United States)

    Lee, E.; Schlosser, C. A.; Gao, X.; Prinn, R. G.

    2011-12-01

    As the impacts between land cover change, future climates and ecosystems are expected to be substantial, there are growing needs for improving the capability of simulating the global vegetation structure and landscape as realistically as possible. Current DGVMs assume ubiquitous availability of seeds and do not consider any seed dispersal mechanisms in plant migration process, which may influence the assessment of impacts to the ecosystem that rely on the vegetation structure changes (i.e., change in albedo, runoff, and terrestrial carbon sequestration capacity). This study incorporates time-varying wind-driven seed dispersal (i.e., the SEED configuration) as a dynamic constraint to the migration process of natural vegetation in the Community Land Model (CLM)-DGVM. The SEED configuration is validated using a satellite-derived tree cover dataset. Then the configuration is applied to project future vegetation structures and their implications for carbon fluxes, albedo, and hydrology under two climate mitigation scenarios (No-policy vs. 450ppm CO2 stabilization) for the 21st century. Our results show that regional changes of vegetation structure under changing climates are expected to be significant. For example, Alaska and Siberia are expected to experience substantial shifts of forestry structure, characterized by expansion of needle-leaf boreal forest and shrinkage of C3 grass Arctic. A suggested vulnerability assessment shows that vegetation structures in Alaska, Greenland, Central America, southern South America, East Africa and East Asia are susceptible to changing climates, regardless of the two climate mitigation scenarios. Regions such as Greenland, Tibet, South Asia and Northern Australia, however, may substantially alleviate their risks of rapid change in vegetation structure, given a robust greenhouse gas stabilization target. Proliferation of boreal forests in the high latitudes is expected to amplify the warming trend (i.e., a positive feedback to

  8. Impact and radiation influence on solid hydrocarbon transformation and structuring (by IR-spectroscopy)

    Science.gov (United States)

    Kovaleva, O.

    2009-04-01

    Solid hydrocarbons (bitumens)-typical specimens of natural organic minerals-are one of the most essential objects of petroleum geology and at the same time-one of the least investigated objects of organic mineralogy. Moreover they can be treated as admissible analogs of meteorite carbonaceous materials. According to terrestrial analog of meteoritic organic matter it's possible to estimate the chemical structure of extraterrestrial matter. Further investigation of impact force and radiation influence on the bitumen chemical structure change will make it possible to connect them with extraterrestrial organic matter. This work represents the research of impact influence on the processes of transformation and structuring of asphaltite and changes in the molecular structure of solid bitumens constituting the carbonization series (asphaltite--kerite--anthraxolite), which were subjected to the impact of high radiation doses (10 and 100 Mrad) by infrared spectroscopy (IRS). In percussion experiments peak pressure varied from 10 to 63.4 GPa; temperature - from the first tens degrees to several hundreds degrees Celsius. The radiation experiment was performed in the Arzamas-16 Federal Nuclear Center in line with conditions described in [1]. Asphaltite, which sustained shock load from 17.3 to 23 GPa, didn't undergo considerable changes in its element composition. Though their IR-spectra differ from the spectrum of initial asphaltite by heightened intensity of absorption bands of aromatic groups, as well as by insignificant rise of heterogroups and condensed structures oscillation strength. At the same time the intensity of aliphatic (СН2 and СН3) groups absorption hasn't changed. Probably there've just been the carbon and hydrogen atomic rearrangement. However, shock load up to 26.7 GPa leads to asphaltite transformation into the albertite. There've been observed the intensity decrease of aliphatic groups on its IR-spectrum. Under growth of shock load up to 60 GPa bitumen

  9. Impact energy analysis of quenched and tempered fine grain structural steel specimens after weld thermal cycle simulation

    Directory of Open Access Journals (Sweden)

    M. Dunđer

    2014-10-01

    Full Text Available The paper presents impact energy results of thermal cycle simulated specimens of quenched and tempered fine grain structural steel S960QL. These results are obtained by examining notched Charpy specimens. Upon performed metallographic analysis and measured hardness, total impact energy is separated into ductile and brittle components.

  10. Asteroid surface archaeology: Identification of eroded impact structures by spectral properties on (4) Vesta

    Science.gov (United States)

    Hoffmann, M.; Nathues, A.; Schäfer, M.; Schmedemann, N.; Vincent, J.; Russell, C.

    2014-07-01

    excavation of deeper layers of Vesta's crust and gradients of space weathering, the latter showing up also at smaller highly eroded craters. As an example of the third type, a global mosaic demonstrates the relationship of reflectance level and band I depth. A non-uniform distribution appears, with an anomaly emerging from the large crater Albana in one of its sectors. This association seems to be caused by ejected material from this crater. Only the spectral signature has remained to identify the original pattern. The spectral properties appear to be related to an enhanced presence of shocked material [3] and impact glass [4]. Conclusions: Today's non-uniformity of impact structures, dominated by the Rheasilvia basin, reflects a singular event in a late stage of Vesta's surface evolution. Some earlier large impacts have left their footprints in specific remnants resembling the cases of lunar cryptomaria [5]. Vesta has escaped the fate of other differentiated protoplanets, which have been disrupted, but the crust has been shattered, which does not change the spatial distribution of the surface material entirely. This is associated with linear fragmentation features of various sizes (grabens, troughs, cracks, pit chains) which are correlated with some of the features described here.

  11. A Comparison Study of Extreme Learning Machine and Least Squares Support Vector Machine for Structural Impact Localization

    OpenAIRE

    Qingsong Xu

    2014-01-01

    Extreme learning machine (ELM) is a learning algorithm for single-hidden layer feedforward neural network dedicated to an extremely fast learning. However, the performance of ELM in structural impact localization is unknown yet. In this paper, a comparison study of ELM with least squares support vector machine (LSSVM) is presented for the application on impact localization of a plate structure with surface-mounted piezoelectric sensors. Both basic and kernel-based ELM regression models have b...

  12. Effect of austenitizing conditions on the impact properties of an alloyed austempered ductile iron of initially ferritic matrix structure

    Science.gov (United States)

    Delia, M.; Alaalam, M.; Grech, M.

    1998-04-01

    The effect of austenitizing conditions on the microstructure and impact properties of an austempered ductile iron (ADI) containing 1.6% Cu and 1.6% Ni as the main alloying elements was investigated. Impact tests were carried out on samples of initially ferritic matrix structure and which had been first austenitized at 850,900, 950, and 1000°C for 15 to 360 min and austempered at 360°C for 180 min. Results showed that the austenitizing temperature, Tγ, and time, tγ, have a significant effect on the impact properties of the alloy. This has been attributed to the influence of these variables on the carbon kinetics. The impact energy is generally high after short tγ, and it falls with further soaking. In samples austenitized at 850 and 900°C, these trends correspond to the gradual disappearance of the pro-eutectoid ferrite and the attainment of fully developed ausferritic structures. In initially ferritic structures, the carbon diffusion distances involved during austenitization are large compared to those in pearlitic structures. This explains the relatively long soaking periods required to attain fully ausferritic structures, which in spite of the lower impact energy values, have a better combination of mechanical properties. Microstructures of samples austenitized at 950 and 1000°C contain no pro-eutectoid ferrite. The impact properties of the former structures are independent of tγ, while those solution treated at 1000°C are generally low and show wide variation over the range of soaking time investigated. For fully ausferritic structures, impact properties fall with an increase in Tγ. This is particularly evident at 1000°C. As the Tγ increases, the amount of carbon dissolved in the original austenite increases. This slows down the rate of austenite transformation and results in coarser structures with lower mechanical properties. Optimum impact properties are obtained following austenitizing between 900 and 950°C for 120 to 180 min.

  13. Impact melt-bearing breccias of the Mistastin Lake impact structure: A unique planetary analogue for ground-truthing proximal ejecta emplacement

    Science.gov (United States)

    Mader, M. M.; Osinski, G. R.

    2013-12-01

    Impact craters are the dominant geological landform on rocky planetary surfaces; however, relationships between specific craters and their ejecta are typically poorly constrained. With limited planetary samples, scientists look to terrestrial craters as analogues. Impact ejecta is defined here as any target material, regardless of its physical state, that is transported beyond the rim of the transient cavity [1]. The original transient cavity reaches its maximum size during the excavation stage of crater formation, before rim collapse begins in the modification stage [2]. In complex craters, during the modification stage, rocks around the periphery of the bowl-shaped transient crater collapse downward and inward to form a series of terraces along the outer margin of the crater structure [3]. Proximal impact ejecta, can therefore be found on the terraces of the modified rim of a complex crater, interior to the final crater rim [1]. Although typically poorly preserved on Earth due to post-impact erosional processes, impact ejecta have been identified in the terraced rim region of the Mistastin Lake impact structure, located in northern Labrador, Canada (55°53'N; 63°18'W) [4]. The Mistastin Lake impact structure is an intermediate-size, complex crater (28 km apparent crater diameter) formed by a meteorite impact ~36 Ma in crystalline target rocks. The original crater has been differentially eroded; however, a terraced rim and distinct central uplift are still observed [5]. The inner portion of the structure is covered by the Mistastin Lake and the surrounding area is locally covered by soil/glacial deposits and vegetation. Locally, allochthonous impactites overlying fractured target rocks are exposed along the lakeshore and along banks of radially cutting streams. They define a consistent stratigraphy, including, from bottom to top: monomict, lithic breccias, allochthonous polymict lithic breccias, and allochthonous impact melt rocks. Mistastin impact breccias range

  14. The capital structure of Polish small and medium-sized enterprises and its impact on their competitiveness

    OpenAIRE

    Robert Wolañski

    2013-01-01

    The article discusses the problem of the relationship between the capital structure and the level of competitiveness of SMEs in Poland. The objective of the article is to determine the impact capital structure has on the level of competitiveness of SMEs in Poland. The capital structure of SMEs is dominated by internal funds. Among external sources of financing, bank loans and leasing are predominant. This structure is consistent with the relevant theoretical models. The study shows no signifi...

  15. Impact of regression methods on improved effects of soil structure on soil water retention estimates

    Science.gov (United States)

    Nguyen, Phuong Minh; De Pue, Jan; Le, Khoa Van; Cornelis, Wim

    2015-06-01

    Increasing the accuracy of pedotransfer functions (PTFs), an indirect method for predicting non-readily available soil features such as soil water retention characteristics (SWRC), is of crucial importance for large scale agro-hydrological modeling. Adding significant predictors (i.e., soil structure), and implementing more flexible regression algorithms are among the main strategies of PTFs improvement. The aim of this study was to investigate whether the improved effect of categorical soil structure information on estimating soil-water content at various matric potentials, which has been reported in literature, could be enduringly captured by regression techniques other than the usually applied linear regression. Two data mining techniques, i.e., Support Vector Machines (SVM), and k-Nearest Neighbors (kNN), which have been recently introduced as promising tools for PTF development, were utilized to test if the incorporation of soil structure will improve PTF's accuracy under a context of rather limited training data. The results show that incorporating descriptive soil structure information, i.e., massive, structured and structureless, as grouping criterion can improve the accuracy of PTFs derived by SVM approach in the range of matric potential of -6 to -33 kPa (average RMSE decreased up to 0.005 m3 m-3 after grouping, depending on matric potentials). The improvement was primarily attributed to the outperformance of SVM-PTFs calibrated on structureless soils. No improvement was obtained with kNN technique, at least not in our study in which the data set became limited in size after grouping. Since there is an impact of regression techniques on the improved effect of incorporating qualitative soil structure information, selecting a proper technique will help to maximize the combined influence of flexible regression algorithms and soil structure information on PTF accuracy.

  16. The Impact of Communication Technologies on Social Structure--Take the Example of Smart City

    Institute of Scientific and Technical Information of China (English)

    Nie Zhou

    2016-01-01

    Human society has entered the era of digit and internet, and the communication technology is one of the important factors which result in changes of social structure. Smart City is an active attempt to future urban development, to use the communication technology as an constitutive element of smart city from the economic base to the superstructure, production relation to exchange relation. Digitization and networking are committed to reflect the state of human's comprehensive development, which is an important stage of emancipation of humanity itself. Communication technology can bring people's initiative into full play and learning in development and establish the harmonious relationships during the interaction. This article is based on the example of smart city, which analyzed the impact of communication technologies on social structure from different aspects.

  17. Jury-Contestant Bipartite Competition Network: Identifying Biased Scores and Their Impact on Network Structure Inference

    CERN Document Server

    Jeon, Gyuhyeon

    2016-01-01

    A common form of competition is one where judges grade contestants' performances which are then compiled to determine the final ranking of the contestants. Unlike in another common form of competition where two contestants play a head-to-head match to produce a winner as in football or basketball, the objectivity of judges are prone to be questioned, potentially undermining the public's trust in the fairness of the competition. In this work we show, by modeling the judge--contestant competition as a weighted bipartite network, how we can identify biased scores and measure their impact on our inference of the network structure. Analyzing the prestigious International Chopin Piano Competition of 2015 with a well-publicized scoring controversy as an example, we show that even a single statistically uncharacteristic score can be enough to gravely distort our inference of the community structure, demonstrating the importance of detecting and eliminating biases. In the process we also find that there does not exist...

  18. EVOLUTIVE AND STRUCTURAL CHANGES OF MOUNTAIN TOURISM WITH IMPACT ON SUSTAINABLE DEVELOPMENT IN ROMANIA

    Directory of Open Access Journals (Sweden)

    RODICA-MANUELA GOGONEA

    2014-05-01

    Full Text Available Following the global economic crisis, sustainable development of tourism in Romania, is still one of the main drivers of economic recovery mechanism. Treated in an integrating vision, sustainable tourism includes a wide range of matters affecting mountain tourism a basic shape of this area of activity. The study highlights the level of development and place of mountain tourism, among other forms of Romanian tourism through evolutionary and structural analysis of the number of structures for tourist arrivals and overnight stays within them. Purposes of determining aspects of mountain tourism development are aiming to detect its impact on sustainable development. However, the overall image of the development of mountain tourism has created the premises for the adoption of strategies for sustainable development of tourism in Romania

  19. Formation of Coherent Structures and Impact on Turbulence Scaling in Solar-Wind Plasma

    Science.gov (United States)

    Nandal, P.; Sharma, Swati; Yadav, N.; Sharma, R. P.

    2016-10-01

    The governing dynamical equations of the right-handed circularly polarized dispersive Alfvén wave (DAW), which becomes dispersive owing to the finite frequency of the wave, and the slow Alfvén wave have been obtained using a two-fluid model. The wave localization at different instants of time and its power spectrum have been investigated. The ponderomotive force associated with the pump wave results in intense localized structures. The steepening of spectra is observed from the inertial range to the dispersive range. The results imply that the DAW may play a significant role in solar-wind turbulence. In addition, the formation of DAW localized structures is further examined considering two primary approaches, parametric instability (filamentation) and the reconnection-based model, to study the impact on the turbulent spectrum in more detail.

  20. Structural integrity of wind turbines impacted by tropical cyclones: A case study from China

    Science.gov (United States)

    Chen, Xiao; Li, Chuanfeng; Tang, Jing

    2016-09-01

    This study presents a case study on wind turbines impacted by tropical cyclones in China. A quantitative investigation is conducted by integrating aerodynamic, aero-elastic and structural analysis to provide insights into structural integrity of wind turbines under extreme wind conditions. Local mean wind profiles at each turbine site are reconstructed using threedimensional CFD calculation considering terrain topography of the wind farm. Failure modes and failure locations of rotor blades and tubular towers are predicted using finite element analysis. “The lesser of two evils” principle in the turbine design is addressed regarding the criticality of blade fracture and tower collapse. Referring to the current IEC standard for wind turbine design, it is suggested that the partial safety factor associated with failure of turbine tower should be larger than, instead of equal to, the one for the rotor blade to reduce the risk of the total loss of wind turbines in extreme wind conditions.

  1. The impact of active controls technology on the structural integrity of aeronautical vehicles

    Science.gov (United States)

    Noll, Thomas E.; Austin, Edward; Donley, Shawn; Graham, George; Harris, Terry; Kaynes, Ian; Lee, Ben; Sparrow, James

    1993-01-01

    The findings of an investigation conducted under the auspices of The Technical Cooperation Program (TTCP) to assess the impact of active controls technology on the structural integrity of aeronautical vehicles and to evaluate the present state-of-the-art for predicting loads caused by a flight-control system modification and the resulting change in the fatigue life of the flight vehicle are summarized. Important points concerning structural technology considerations implicit in applying active controls technology in new aircraft are summarized. These points are well founded and based upon information received from within the aerospace industry and government laboratories, acquired by sponsoring workshops which brought together experts from contributing and interacting technical disciplines, and obtained by conducting a case study to independently assess the state of the technology. The paper concludes that communication between technical disciplines is absolutely essential in the design of future high performance aircraft.

  2. Faunal impact on vegetation structure and ecosystem function in mangrove forests: A review

    Science.gov (United States)

    Cannicci, Stefano; Burrows, Damien; Fratini, Sara; Smith, Thomas J.; Offenberg, Joachim; Dahdouh-Guebas, Farid

    2008-01-01

    The last 20 years witnessed a real paradigm shift concerning the impact of biotic factors on ecosystem functions as well as on vegetation structure of mangrove forests. Before this small scientific revolution took place, structural aspects of mangrove forests were viewed to be the result of abiotic processes acting from the bottom-up, while, at ecosystem level, the outwelling hypothesis stated that mangroves primary production was removed via tidal action and carried to adjacent nearshore ecosystems where it fuelled detrital based food-webs. The sesarmid crabs were the first macrofaunal taxon to be considered a main actor in mangrove structuring processes, thanks to a number of studies carried out in the Indo-Pacific forests in the late 1970s and early 1980s. Following these classical papers, a number of studies on Sesarmidae feeding and burrowing ecology were carried out, which leave no doubts about the great importance of these herbivorous crabs in structuring and functioning Old world ecosystems. Although Sesarmidae are still considered very important in shaping mangrove structure and functioning, recent literature emphasizes the significance of other invertebrates. The Ocypodidae have now been shown to have the same role as Sesarmidae in terms of retention of forest products and organic matter processing in New world mangroves. In both New and Old world mangroves, crabs process large amounts of algal primary production, contribute consistently to retention of mangrove production and as ecosystem engineers, change particle size distribution and enhance soil aeration. Our understanding of the strong impact of gastropods, by means of high intake rates of mangrove products and differential consumption of propagules, has changed only recently. The role of insects must also be stressed. It is now clear that older techniques used to assess herbivory rates by insects strongly underestimate their impact, both in case of leaf eating and wood boring species and that

  3. Combined Structural and Compositional Evolution of Planetary Rings Due to Micrometeoroid Impacts and Ballistic Transport

    Science.gov (United States)

    Estrada, Paul R.; Durisen, Richard H.; Cuzzi, Jeffrey N.; Morgan, Demitri A.

    2015-01-01

    We introduce improved numerical techniques for simulating the structural and compositional evolution of planetary rings due to micrometeoroid bombardment and subsequent ballistic transport of impact ejecta. Our current, robust code is capable of modeling structural changes and pollution transport simultaneously over long times on both local and global scales. In this paper, we describe the methodology based on the original structural code of Durisen et al. (1989, Icarus 80, 136-166) and on the pollution transport code of Cuzzi and Estrada (1998, Icarus 132, 1-35). We provide demonstrative simulations to compare with, and extend upon previous work, as well as examples of how ballistic transport can maintain the observed structure in Saturn's rings using available Cassini occultation optical depth data. In particular, we explicitly verify the claim that the inner B (and presumably A) ring edge can be maintained over long periods of time due to an ejecta distribution that is heavily biased in the prograde direction through a balance between the sharpening effects of ballistic transport and the broadening effects of viscosity. We also see that a "ramp"-like feature forms over time just inside that edge. However, it does not remain linear for the duration of the runs presented here unless a less steep ejecta velocity distribution is adopted. We also model the C ring plateaus and find that their outer edges can be maintained at their observed sharpness for long periods due to ballistic transport. We hypothesize that the addition of a significant component of a retrograde-biased ejecta distribution may help explain the linearity of the ramp and is probably essential for maintaining the sharpness of C ring plateau inner edges. This component would arise for the subset of micrometeoroid impacts which are destructive rather than merely cratering. Such a distribution will be introduced in future work.

  4. Impact Of Firm Specific Factors On Capital Structure Decision: An Empirical Study Of Albanian Firms.

    Directory of Open Access Journals (Sweden)

    Anila Çekrezi

    2013-04-01

    Full Text Available This paper attempts to explore the impact of firm specific factors on capital structuredecision for a sample of 65 non- listed firms, which operate in Albania, over the period2008-2011.In this paper are used three capital structure measures ; short –term debt tototal assets (STDA, long- term debt to total assets (LTDA and total debt to total assets(TDTA as dependent variables and four dependent variables: tangibility(TANG,liquidity (LIQ, profitability(ROA=return on assets and size (SIZE. The investigationuses panel data procedure and the data are taken from balance sheets and include onlyaccounting measures on the firm’s leverage. This study found that tangibility (the ratio offixed assets to total assets, liquidity (the ratio of current assets to current liabilitiesprofitability (the ratio of earnings after taxes to total assets and size (natural logarithm oftotal assets have a significant impact on leverage. Also empirical evidence reveals asignificant negative relation of ROA to leverage and a significant positive relation ofSIZE to leverage. And the second objective of this study is to identify the impact ofindustry classification on firm’s leverage, using a dummy variable for the trade sector. Soone of the hypothesis tested is if financial leverage is independent of industryclassification. Results reveal that long term debt to total assets and total debt to totalassets ratios are significantly different across Albanian industries.

  5. Experimental impact features in Stardust aerogel: How track morphology reflects particle structure, composition, and density

    Science.gov (United States)

    Kearsley, Anton T.; Burchell, Mark J.; Price, Mark C.; Cole, Michael J.; Wozniakiewicz, Penelope J.; Ishii, Hope A.; Bradley, John P.; Fries, Marc; Foster, Nicholas J.

    2012-04-01

    The Stardust collector shows diverse aerogel track shapes created by impacts of cometary dust. Tracks have been classified into three broad types (A, B, and C), based on relative dimensions of the elongate "stylus" (in Type A "carrots") and broad "bulb" regions (Types B and C), with occurrence of smaller "styli" in Type B. From our experiments, using a diverse suite of projectile particles shot under Stardust cometary encounter conditions onto similar aerogel targets, we describe differences in impactor behavior and aerogel response resulting in the observed range of Stardust track shapes. We compare tracks made by mineral grains, natural and artificial aggregates of differing subgrain sizes, and diverse organic materials. Impacts of glasses and robust mineral grains generate elongate, narrow Type A tracks (as expected), but with differing levels of abrasion and lateral branch creation. Aggregate particles, both natural and artificial, of a wide range of compositions and volatile contents produce diverse Type B or C shapes. Creation of bulbous tracks is dependent upon impactor internal structure, grain size distribution, and strength, rather than overall grain density or content of volatile components. Nevertheless, pure organic particles do create Type C, or squat Type A* tracks, with length to width ratios dependent upon both specific organic composition and impactor grain size. From comparison with the published shape data for Stardust aerogel tracks, we conclude that the abundant larger Type B tracks on the Stardust collector represent impacts by particles similar to our carbonaceous chondrite meteorite powders.

  6. Palaeomagnetism of the Permo-Triassic Araguainha impact structure (Central Brazil) and implications for Pangean reconstructions

    Science.gov (United States)

    Yokoyama, Elder; Brandt, Daniele; Tohver, Eric; Trindade, Ricardo I. F.

    2014-07-01

    The configuration of the Pangea supercontinent has been a topic of intense debate for almost half a century, a controversy that stems from discrepancies between the geology-based Pangea-A and the palaeomagnetically based Pangea-B. Recent palaeomagnetic compilations aimed at resolving this controversy have identified the poor quality of palaeomagnetic data from Gondwana for Permian times as a major obstacle. Specifically, the vast majority of Gondwanan poles come from sedimentary rocks that are prone to biases from compaction or are poorly dated. Here, we present a new palaeomagnetic pole for cratonic South America based on impact melts from the 254.7 ± 2.5 Ma Araguainha impact structure (AIS). The granite basement, the impact-generated melt sheet and veins were sampled at 28 sites (169 specimens) and provided a reliable palaeomagnetic record similar to that of volcanic rocks. Alternating field and thermal demagnetization indicate a stable characteristic remanent magnetization carried by both magnetite and haematite. All sites but one show a single palaeomagnetic direction of normal polarity with a mean direction of Dec = 357.4°; Inc = -38.9°; N = 28; k = 62.35; α95 = 3.5°, yielding a palaeomagnetic pole (AIS) at Lat = -84.2; Lon = 326.6; K = 83.5; A95 = 3.6°; SB = 9.6°. The new pole provides a firm constraint on the position of Gondwana which is consistent with the Pangea A configuration.

  7. Impact of Mountain Pine Beetle Infestation on Snowmelt: Variations with Vegetation Structure and Geographical Locations

    Science.gov (United States)

    Ni-Meister, W.

    2015-12-01

    The warming climate resulted in the current outbreak of mountain pine beetles (MPB) in western and northwestern US. and Western Canada. Colorado, Wyoming, South Dakota, Nebraska, and British Columbia are also currently experiencing widespread mountain pine beetle infestations. Forest disturbance due to MPB can have a large impact on hydrological processes specifically snow accumulation and snowmelt. In those regions, spring snowmelt is a major water resource and MPB infestations can have a big impact on water resource management. MPB infestations cause forest canopies to gradually diminish over the course of several years, they therefore impact snow interception and radiation balance at snow surface, thus snowmelt. Past studies on this topic have achieved contradicting results. This study focuses on understanding how the impacts of MPB infestations on snow surface radiation balance and snowmelt rates vary with vegetation structure and geographical locations. We selected four sites in northern Colorado and four sites in the Cascade Mountains in Oregon with varying intensities of MPB. Snow Water Equivalent (SWE) data from SNOTEL sites and MPB-caused forest disturbance data extracted from Landsat time series disturbance maps were used for our analysis. Our results show that MPB sites show larger snow accumulation for sites in Colorado and Cascade Mountains. However snowmelt rate varies differently. For sites in Colorado, snow melts faster in the MPB sites than in the healthy forest sites. In contrary, in the Cascade Mountains, snow stays longer in MPB sites than in healthy and undisturbed sites. Our modeling study shows that shortwave radiation is a dominant factor for radiation balance in the mid-latitude region (Colorado). There, MPB infestations lead to increased shortwave radiation and faster snowmelt. However, long wave radiation plays an important role for radiation balance in high latitude areas. MPB infestations decrease longwave radiation and result in snow

  8. Frictional melting processes and the generation of shock veins in terrestrial impact structures: Evidence from the Steen River impact structure, Alberta, Canada

    Science.gov (United States)

    Walton, Erin L.; Sharp, Thomas G.; Hu, Jinping

    2016-05-01

    Shock-produced melt within crystalline basement rocks of the Steen River impact structure (SRIS) are observed as thin (1-510 μm wide), interlocking networks of dark veins which cut across and displace host rock minerals. Solid-state phase transformations, such as ferro-pargasite to an almandine-andradite-majorite garnet and amorphization of quartz and feldspar, are observed in zones adjacent to comparatively wider (50-500 μm) sections of the shock veins. Shock pressure estimates based on the coupled substitution of Na+, Ti4+ and Si4+ for divalent cations, Al3+ and Cr3+ in garnet (14-19 GPa) and the pressure required for plagioclase (Ab62-83) amorphization at elevated temperature (14-20 GPa) are not appreciably different from those recorded by deformation effects observed in non-veined regions of the bulk rock (14-20 GPa). This spatial distribution is the result of an elevated temperature gradient experienced by host rock minerals in contact with larger volumes of impact-generated melt and large deviatoric stresses experienced by minerals along vein margins. Micrometer-size equant crystals of almandine-pyrope-majorite garnet define the shock vein matrix, consistent with rapid quench (100-200 ms) at 7.5-10 GPa. Crystallization of the vein occurred during a 0.1-0.15 s shock pressure pulse. Majoritic garnet, formed during shock compression by solid state transformation of pargasite along shock vein margins, is observed in TEM bright field images as nanometer-size gouge particles produced at strain rates in the supersonic field (106-108). These crystals are embedded in vesiculated glass, and this texture is interpreted as continued movement and heating along slip planes during pressure release. The deformation of high-pressure minerals formed during shock compression may be the first evidence of oscillatory slip in natural shock veins, which accounts for the production of friction melt via shear when little or no appreciable displacement is observed. Our observations

  9. Environmental impact assessment of a WtE plant after structural upgrade measures.

    Science.gov (United States)

    Passarini, Fabrizio; Nicoletti, Monica; Ciacci, Luca; Vassura, Ivano; Morselli, Luciano

    2014-04-01

    The study focuses on analysing the evolution of environmental impacts caused by a medium-large Italian WtE plant before and after revamping and maintenance operations, with the aim of providing an evaluation of how much these structural upgrade measures may affect the total environmental performance. LCA methodology was applied for the modelling and comparison of six WtE scenarios, each describing the main structural upgrades carried out in the plant over the years 1996-2011. The comparison was conducted by adopting 1ton of MSW as the functional unit, and the net contribution from energy recovery to power generation was distinguished by defining consistent national grid electricity mixes for every year considered. The Ecoindicator99 2.09 impact assessment method was used to evaluate the contribution to midpoint and endpoint categories (e.g. carcinogens, respiratory inorganics and organics, climate change, damage to human health). Lastly, the "Pedigree quality matrix" was applied to verify the reliability and robustness of the model created. As expected, the results showed better environmental scores after both the implementation of new procedures and the integration of operations. However, while a net reduction of air emissions seems to be achievable through dedicated flue gas treatment technologies, outcomes underscored potentials for improving the management of bottom ash through the adoption of alternative options aimed to use that solid residue mainly as filler, and to decrease risks from its current disposal in landfill. If the same effort that is put into flue gas treatment were devoted to energy recovery, the targets for the WtE plant could be easily met, achieving a higher sustainability. This aspect is even more complex: national policies for implementing greener and renewable energy sources would result in a lower impact of the national energy mix and, hence, in a lower net avoided burden from energy recovery. The study confirmed the expected improvements

  10. Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

    Science.gov (United States)

    Ryan, Shannon; Christiansen, Eric; Lear, Dana

    2009-01-01

    Metallic foams are a relatively new class of materials with low density and novel physical, mechanical, thermal, electrical and acoustic properties. Although incompletely characterized, they offer comparable mechanical performance to traditional spacecraft structural materials (i.e. honeycomb sandwich panels) without detrimental through-thickness channeling cells. There are two competing types of metallic foams: open cell and closed cell. Open cell foams are considered the more promising technology due to their lower weight and higher degree of homogeneity. Leading micrometeoroid and orbital debris shields (MMOD) incorporate thin plates separated by a void space (i.e. Whipple shield). Inclusion of intermediate fabric layers, or multiple bumper plates have led to significant performance enhancements, yet these shields require additional non-ballistic mass for installation (fasteners, supports, etc.) that can consume up to 35% of the total shield weight [1]. Structural panels, such as open cell foam core sandwich panels, that are also capable of providing sufficient MMOD protection, represent a significant potential for increased efficiency in hypervelocity impact shielding from a systems perspective through a reduction in required non-ballistic mass. In this paper, the results of an extensive impact test program on aluminum foam core sandwich panels are reported. The effect of pore density, and core thickness on shielding performance have been evaluated over impact velocities ranging from 2.2 - 9.3 km/s at various angles. A number of additional tests on alternate sandwich panel configurations of comparable-weight have also been performed, including aluminum honeycomb sandwich panels (see Figure 1), Nomex honeycomb core sandwich panels, and 3D aluminum honeycomb sandwich panels. A total of 70 hypervelocity impact tests are reported, from which an empirical ballistic limit equation (BLE) has been derived. The BLE is in the standard form suitable for implementation in

  11. Debris flow impact on mitigation barriers: a new method for particle-fluid-structure interactions

    Science.gov (United States)

    Marchelli, Maddalena; Pirulli, Marina; Pudasaini, Shiva P.

    2016-04-01

    Channelized debris-flows are a type of mass movements that involve water-charged, predominantly coarse-grained inorganic and organic material flowing rapidly down steep confined pre-existing channels (Van Dine, 1985). Due to their rapid movements and destructive power, structural mitigation measures have become an integral part of counter measures against these phenomena, to mitigate and prevent damages resulting from debris-flow impact on urbanized areas. In particular, debris barriers and storage basins, with some form of debris-straining structures incorporated into the barrier constructed across the path of a debris-flow, have a dual role to play: (1) to stimulate deposition by presenting a physical obstruction against flow, and (2) to guarantee that during normal conditions stream water and bedload can pass through the structure; while, during and after an extreme event, the water that is in the flow and some of the fine-grained sediment can escape. A new method to investigate the dynamic interactions between the flowing mass and the debris barrier is presented, with particular emphasis on the effect of the barrier in controlling the water and sediment content of the escaping mass. This aspect is achieved by implementing a new mechanical model into an enhanced two-phase dynamical mass flow model (Pudasaini, 2012), in which solid particles mixture and viscous fluid are taken into account. The complex mechanical model is defined as a function of the energy lost during impact, the physical and geometrical properties of the debris barrier, separate but strongly interacting dynamics of boulder and fluid flows during the impact, particle concentration distribution, and the slope characteristics. The particle-filtering-process results in a large variation in the rheological properties of the fluid-dominated escaping mass, including the substantial reduction in the bulk density, and the inertial forces of the debris-flows. Consequently, the destructive power and run

  12. Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland

    Science.gov (United States)

    Raiskila, Selen; Salminen, Johanna; Elbra, Tiiu; Pesonen, Lauri J.

    2011-11-01

    There are 31 proven impact structures in Fennoscandia—one of the most densely crater-populated areas of the Earth. The recently discovered Keurusselkä impact structure (62°08' N, 24°37' E) is located within the Central Finland Granitoid Complex, which formed 1890-1860 Ma ago during the Svecofennian orogeny. It is a deeply eroded complex crater that yields in situ shatter cones with evidence of shock metamorphism, e.g., planar deformation features in quartz. New petrophysical and rock magnetic results of shocked and unshocked target rocks of various lithologies combined with paleomagnetic studies are presented. The suggested central uplift with shatter cones is characterized by increased magnetization and susceptibility. The presence of magnetite and pyrrhotite was observed as carriers for the remanent magnetization. Four different remanent magnetization directions were isolated: (1) a characteristic Svecofennian target rock component A with a mean direction of D = 334.8°, I = 45.6°, α95 = 14.9° yielding a pole (Plat = 51.1°, Plon = 241.9°, A95 = 15.1°), (2) component B, D = 42.4°, I = 64.1°, α95 = 8.4° yielding a pole (Plat = 61.0°, Plon = 129.1°, A95 = 10.6°), (3) component C (D = 159.5°, I = 65.4°, α95 = 10.7°) yielding a pole (Plat = 21.0°, Plon = 39.3°, A95 = 15.6°), and (4) component E (D = 275.5°, I = 62.0°, α95 = 14.4°) yielding a pole (Plat = 39.7°, Plon = 314.3°, A95 = 19.7°). Components C and E are considered much younger, possibly Neoproterozoic overprints, compared with the components A and B. The pole of component B corresponds with the 1120 Ma pole of Salla diabase dyke and is in agreement with the 40Ar/39Ar age of 1140 Ma from a pseudotachylitic breccia vein in a central part of the structure. Therefore, component B could be related to the impact, and thus represent the impact age.

  13. Methods for Progressive Collapse Analysis of Building Structures Under Blast and Impact Loads

    Institute of Scientific and Technical Information of China (English)

    LI Zhongxian; SHI Yanchao

    2008-01-01

    Progressive collapse of building structures under blast and impact lcads has attracted great attention all over the world.Prog ressive collapse analysis is essential for an economic and safe design of building structures against progressive collapse to blast and impact loads.Because of the catastrophic nature of progressive collapse and the potentially high cost of constructing or retrofitting buildings to resist it,is imperative that the progressive collapse analysis methods be reliable.For engineers.their methodology to carry out progressve collapse evaluation need not only be accurate and concise.but also be easily used and works fast.Thus,many researchers have been spending lots of effort in developing reliable,efficient and strajghtforward progressive collapse analysis methods recently.In the present paper,currenf progresslve collapse analysis meth ods available in the literature are reviewed.Their suitability,applicability and reliability are dis cussed.Our recent proposed new method for progressive collapse analysis of relnforced concrete frames under blast lcads is also introduced.

  14. Breakdown pathways during oral processing of different breads: impact of crumb and crust structures.

    Science.gov (United States)

    Jourdren, S; Panouillé, M; Saint-Eve, A; Déléris, I; Forest, D; Lejeune, P; Souchon, I

    2016-03-01

    Oral processing during bread consumption is a key process related to the dynamics of texture perceptions, sensory stimuli release and starch digestion. The aim of this study was to determine the respective contribution of bread properties (composition and structure of crumb and crust) and of the oral physiology of subjects to the breakdown pathways in the mouth. The properties of the in vivo bread bolus obtained from eight healthy subjects were studied at three key points in time during their oral processing. The progressive lubrication and breakdown of bread were observed, as well as the beginning of the enzymatic degradation of starch. The study showed that "time" was the factor responsible for the greatest variability in bolus properties. Breakdown pathways were established for crumbs with and without crust. The presence of crust modified the oral processing, increasing, for instance, the heterogeneity of particle size at the middle of the oral processing sequence. Moreover, the hydration capacity of crust contributed to high starch degradation at swallowing time, in comparison with crumb alone. The main subject characteristics impacting bolus properties were the in-mouth duration, the individual masticatory index and the mouth volume, while the main bread properties explaining the bolus properties were the initial composition and the water-absorbing capacity. We concluded that both crumb and crust structures had an impact on the oral processing, affecting the capacity of hydration, the rheology and the breakdown degree of the bolus.

  15. Near-complete structural characterization of phosphatidylcholines using electron impact excitation of ions from organics.

    Science.gov (United States)

    Campbell, J Larry; Baba, Takashi

    2015-06-02

    Although lipids are critical components of many cellular assemblies and biological pathways, accurate descriptions of their molecular structures remain difficult to obtain. Many benchtop characterization methods require arduous and time-consuming procedures, and multiple assays are required whenever a new structural feature is probed. Here, we describe a new mass-spectrometry-based workflow for enhanced structural lipidomics that, in a single experiment, can yield almost complete structural information for a given glycerophospholipid (GPL) species. This includes the lipid's sum (Brutto) composition from the accurate mass measured for the intact lipid ion and the characteristic headgroup fragment, the regioisomer composition from fragment ions unique to the sn-1 and sn-2 positions, and the positions of carbon-carbon double bonds in the lipid acyl chains. Here, lipid ions are fragmented using electron impact excitation of ions from organics (EIEIO)--a technique where the singly charged lipid ions are irradiated by an electron beam, producing diagnostic product ions. We have evaluated this methodology on various lipid standards, as well as on a biological extract, to demonstrate this new method's utility.

  16. Molecular and structural organization of lipids in foods: their fate during digestion and impact in nutrition

    Directory of Open Access Journals (Sweden)

    Meynier Anne

    2017-03-01

    Full Text Available Lipids are basic constituents of our diet. They play an active part in the acceptability, flavour and perception of our foods. At the same time, they are also regarded as beneficial for health or as sources to various pathologies. Until now, the nutritional impact of the various dietary lipid structures beyond the amounts of ingested lipids and selected fatty acids has been marginally taken into account in nutritional studies and thus in food application. This review gathers first our current knowledge on the diversity of molecular and supramolecular structures of dietary lipids, and then based on the scientific studies carried out on the human model, tempts to sum up the current knowledge and the latest hypotheses concerning the metabolic and nutritional effects of these multiscale structures. It is shown that the perception of lipids in the mouth during oral processing modulates the production of digestive fluids and food intake. Then, during the stomach and intestine phases of lipid digestion, the kinetics of release of the fatty acids are modulated by the multiscale structures of lipids influencing the fatty acid bioaccessibility and rate of absorption. In turn this may impair the post-absorption metabolism and nutritional effects. Future trends of research are evoked as concluding remarks.

  17. Denitrification in agriculturally impacted streams: seasonal changes in structure and function of the bacterial community.

    Directory of Open Access Journals (Sweden)

    Erin Manis

    Full Text Available Denitrifiers remove fixed nitrogen from aquatic environments and hydrologic conditions are one potential driver of denitrification rate and denitrifier community composition. In this study, two agriculturally impacted streams in the Sugar Creek watershed in Indiana, USA with different hydrologic regimes were examined; one stream is seasonally ephemeral because of its source (tile drainage, whereas the other stream has permanent flow. Additionally, a simulated flooding experiment was performed on the riparian benches of the ephemeral stream during a dry period. Denitrification activity was assayed using the chloramphenicol amended acetylene block method and bacterial communities were examined based on quantitative PCR and terminal restriction length polymorphisms of the nitrous oxide reductase (nosZ and 16S rRNA genes. In the stream channel, hydrology had a substantial impact on denitrification rates, likely by significantly lowering water potential in sediments. Clear patterns in denitrification rates were observed among pre-drying, dry, and post-drying dates; however, a less clear scenario was apparent when analyzing bacterial community structure suggesting that denitrifier community structure and denitrification rate were not strongly coupled. This implies that the nature of the response to short-term hydrologic changes was physiological rather than increases in abundance of denitrifiers or changes in composition of the denitrifier community. Flooding of riparian bench soils had a short-term, transient effect on denitrification rate. Our results imply that brief flooding of riparian zones is unlikely to contribute substantially to removal of nitrate (NO3- and that seasonal drying of stream channels has a negative impact on NO3- removal, particularly because of the time lag required for denitrification to rebound. This time lag is presumably attributable to the time required for the denitrifiers to respond physiologically rather than a change

  18. UNAM Scientific Drilling Program of Chicxulub Impact Structure-Evidence for a 300 kilometer crater diameter

    Science.gov (United States)

    Urrutia-Fucugauchi, J.; Marin, L.; Trejo-Garcia, A.

    As part of the UNAM drilling program at the Chicxulub structure, two 700 m deep continuously cored boreholes were completed between April and July, 1995. The Peto UNAM-6 and Tekax UNAM-7 drilling sites are ˜150 km and 125 km, respectively, SSE of Chicxulub Puerto, near the crater's center. Core samples from both sites show a sequence of post-crater carbonates on top of a thick impact breccia pile covering the disturbed Mesozoic platform rocks. At UNAM-7, two impact breccia units were encountered: (1) an upper breccia, mean magnetic susceptibility is high (˜55 × 10-6 SI units), indicating a large component of silicate basement has been incorporated into this breccia, and (2) an evaporite-rich, low susceptibility impact breccia similar in character to the evaporite-rich breccias observed at the PEMEX drill sites further out. The upper breccia was encountered at ˜226 m below the surface and is ˜125 m thick; the lower breccia is immediately subjacent and is >240 m thick. This two-breccia sequence is typical of the suevite-Bunte breccia sequence found within other well preserved impact craters. The suevitic upper unit is not present at UNAM-6. Instead, a >240 m thick evaporite-rich breccia unit, similar to the lower breccia at UNAM-7, was encountered at a depth of ˜280 m. The absence of an upper breccia equivalent at UNAM-6 suggests some portion of the breccia sequence has been removed by erosion. This is consistent with interpretations that place the high-standing crater rim at 130-150 km from the center. Consequently, the stratigraphic observations and magnetic susceptibiity records on the upper and lower breccias (depth and thickness) support a ˜300 km diameter crater model.

  19. Polygonal impact craters on Dione: Evidence for tectonic structures outside the wispy terrain

    Science.gov (United States)

    Beddingfield, Chloe B.; Burr, Devon M.; Tran, Liem T.

    2016-08-01

    Plan-view impact crater geometries can be indicative of pre-impact structures within the target material. Impact events that occur on a pre-fractured surface generate craters exhibiting one or more straight rim segments, termed polygonal impact craters (PICs). Impact craters that appear to be PICs are abundant on the surface of Saturn's icy satellite, Dione, both within the wispy terrain, a region with large visible fractures, and also outside the wispy terrain (the 'non-wispy terrain'), where less evidence for fracturing has been observed. In the non-wispy terrain, subtle lineaments are hypothesized to be NE-SW, NW-SE, and E-W trending fractures, suggesting that tectonism may have been an important process in this terrain. Results of previous studies have shown that PIC straight rim segment azimuths ('PIC azimuths') commonly parallel pre-impact fracture azimuths, although disagreements about this relationship exist in the literature. We investigated the hypothesis that fractures, either subtle or nonvisible with available spacecraft images, are present within Dione's non-wispy terrain. Our first step was to assess the relationship between PICs and pre-existing fracture azimuths in the wispy terrain. Our results from this initial assessment show a parallel relationship between PIC azimuths and fracture azimuths. Based on this correlation in the wispy terrain, we find it likely that this relationship would hold true in the non-wispy terrain if PICs are present. We tested for PICs using crater rim azimuth data collected from randomly distributed study locations throughout the non-wispy terrain. From these data, we identified widespread PICs in this terrain, which supports the hypothesis that subtle fractures are also present. Analysis of the PIC azimuth data yield a pattern for these inferred fractures across Dione's surface that is consistent with the hypothesized global deformation that would result from a combination of satellite despinning and volume expansion

  20. Shatter cones and planar deformation features confirm Santa Marta in Piauí State, Brazil, as an impact structure

    Science.gov (United States)

    Oliveira, Grace Juliana Gonçalves; Vasconcelos, Marcos Alberto Rodrigues; Crósta, Alvaro Penteado; Reimold, Wolf Uwe; Góes, Ana Maria; Kowitz, Astrid

    2014-10-01

    A total of 184 confirmed impact structures are known on Earth to date, as registered by the Earth Impact Database. The discovery of new impact structures has progressed in recent years at a rather low rate of about two structures per year. Here, we introduce the discovery of the approximately 10 km diameter Santa Marta impact structure in Piauí State in northeastern Brazil. Santa Marta is a moderately sized complex crater structure, with a raised rim and an off-center, approximately 3.2 km wide central elevated area interpreted to coincide with the central uplift of the impact structure. The Santa Marta structure was first recognized in remote sensing imagery and, later, by distinct gravity and magnetic anomalies. Here, we provide results obtained during the first detailed ground survey. The Bouguer anomaly map shows a transition from a positive to a negative anomaly within the structure along a NE-SW trend, which may be associated with the basement signature and in parts with the signature developed after the crater was formed. Macroscopic evidence for impact in the form of shatter cones has been found in situ at the base around the central elevated plateau, and also in the interior of fractured conglomerate boulders occurring on the floor of the surrounding annular basin. Planar deformation features (PDFs) are abundant in sandstones of the central elevated plateau and at scattered locations in the inner part of the ring syncline. Together, shatter cones and PDFs provide definitive shock evidence that confirms the impact origin of Santa Marta. Crystallographic orientations of PDFs occurring in multiple sets in quartz grains are indicative of peak shock pressures of 20-25 GPa in the rocks exposed at present in the interior of the crater. In contrast to recent studies that have used additional, and sometimes highly controversial, alleged shock recognition features, Santa Marta was identified based on well-understood, traditional shock evidence.

  1. Impact Pseudostatic Load Equivalent Model and the Maximum Internal Force Solution for Underground Structure of Tunnel Lining

    Directory of Open Access Journals (Sweden)

    Xuan Guo

    2016-01-01

    Full Text Available The theoretical formula of the maximum internal forces for circular tunnel lining structure under impact loads of the underground is deduced in this paper. The internal force calculation formula under different equivalent forms of impact pseudostatic loads is obtained. Furthermore, by comparing the theoretical solution with the measured data of the top blasting model test of circular formula under different equivalent forms of impact pseudostatic loads are obtained. Furthermore, by comparing the theoretical solution with the measured data of the top blasting model test of circular tunnel, it is found that the proposed theoretical results accord with the experimental values well. The corresponding equivalent impact pseudostatic triangular load is the most realistic pattern of all test equivalent forms. The equivalent impact pseudostatic load model and maximum solution of the internal force for tunnel lining structure are partially verified.

  2. Modeling of Global BEAM Structure for Evaluation of MMOD Impacts to Support Development of a Health Monitoring System

    Science.gov (United States)

    Lyle, Karen H.; Vassilakos, Gregory J.

    2015-01-01

    This report summarizes the initial modeling of the global response of the Bigelow Expandable Activity Module (BEAM) to micrometeorite and orbital debris(MMOD) impacts using a structural, nonlinear, transient dynamic, finite element code. These models complement the on-orbit deployment of the Distributed Impact Detection System (DIDS) to support structural health monitoring studies. Two global models were developed. The first focused exclusively on impacts on the soft-goods (fabric-envelop) portion of BEAM. The second incorporates the bulkhead to support understanding of bulkhead impacts. These models were exercised for random impact locations and responses monitored at the on-orbit sensor locations. The report concludes with areas for future study.

  3. Impact of different urban structures on the microclimate in the city of Dresden, Germany

    Science.gov (United States)

    Kurbjuhn, Cornelia; Goldberg, Valeri; Westbeld, Anna; Bernhofer, Christian

    2010-05-01

    Heat island intensity of cities and, therefore, urban warming mainly depends on the density of urban structures and sealing of urban areas. Against the background of a probable increase of summer temperature in Central Europe, actual urban planning strategies should consider the importance of open areas and vegetation in the centre of cities for the urban microclimate. This study deals with the interaction between open areas and vegetation structures in the urban micro climate of Dresden. Investigations are embedded in the project "city nature and open area structures under climate change" of the German Federal Agency for Nature Conservation which aims to demonstrate impacts of different urban structures based on climatic factors and to identify their capability for adaptation. Main topic of this research is the determination of the capabilities of given and potentially vegetated areas and open areas in the inner city of Dresden to attenuate microclimatic extremes. The diversity of impacts of vegetated and open areas on the urban microclimate is presented by mobile bicycle measurements and model simulations. Simulations were carried out with the coupled vegetation-boundary layer model HIRVAC-2D and the three-dimensional microclimate model ENVI-met. Model output was compared to measurements of air temperature and air humidity on sunny days in the year 2009 to quantify cooling effects of vegetated areas for summer heat periods. ENVI-met is designed to simulate the surface-plant-atmosphere interactions in urban environment and allows the derivation of bioclimatic factors like Predicted Mean Vote (PMV) for different urban structures. PMV describes the thermal perception of a human body which can result in cold or heat stress. Simulations with ENVI-met were carried out to define the cooling effects of urban areas and to estimate microclimate effects on humans. HIRVAC quantifies the interactions of urban structures with the atmospheric boundary layer depending on area

  4. Multilevel spatial structure impacts on the pollination services of Comarum palustre (Rosaceae).

    Science.gov (United States)

    Somme, Laurent; Mayer, Carolin; Jacquemart, Anne-Laure

    2014-01-01

    Habitat destruction and fragmentation accelerate pollinator decline, consequently disrupting ecosystem processes such as pollination. To date, the impacts of multilevel spatial structure on pollination services have rarely been addressed. We focused on the effects of population spatial structure on the pollination services of Comarum palustre at three levels (i.e. within-population, between-populations and landscape). For three years, we investigated 14 Belgian populations, which differed in their within-population flower density, population surface, closure (i.e. proportion of the population edge that consisted of woody elements) and isolation (i.e. percentage of woody area cover within a 500 m radius from the population centre). We tested whether these spatial characteristics impact on pollinator abundance and visitation rate and thus, reproductive success of C. palustre. Insects were observed in 15 randomly-chosen plots in each population. We tested for pollen limitation with supplemental hand-cross pollination. Bumble bees and solitary bees were the major pollinators through all populations. Within populations, plots with high flower densities attracted high numbers of bumble bees and other insects. High bumble bee and solitary bee abundance was observed in populations presenting high proportions of woody edges and in populations within landscapes presenting high proportions of woody areas. Seed set resulting from open pollination varied with bumble bee and solitary bee visitation rate, leading to increased pollen limitation when pollinators were scarce. Since the reproductive success depended on the visitation rate of the main pollinators, which depended on multilevel spatial structure, wetland management plans should pay special attention to favour a mosaic of biotopes, including nesting sites and food resources for insects. This study particularly supports the relevance of a mix wetlands and woody habitats to bees.

  5. The impacts of triclosan on anaerobic community structures, function, and antimicrobial resistance.

    Science.gov (United States)

    McNamara, Patrick J; LaPara, Timothy M; Novak, Paige J

    2014-07-01

    Triclosan is a widespread antimicrobial agent that accumulates in anaerobic digesters used to treat the residual solids generated at municipal wastewater treatment plants; there is very little information, however, about how triclosan impacts microbial communities in anaerobic digesters. We investigated how triclosan impacts the community structure, function and antimicrobial resistance genes in lab-scale anaerobic digesters. Previously exposed (to triclosan) communities were amended with 5, 50, and 500 mg/kg of triclosan, corresponding to the median, 95th percentile, and 4-fold higher than maximum triclosan concentration that has been detected in U.S. biosolids. Triclosan amendment caused all of the Bacteria and Archaea communities to structurally diverge from that of the control cultures (based on ARISA). At the end of the experiment, all triclosan-amended Archaea communities had diverged from the control communities, regardless of the triclosan concentration added. In contrast, over time the Bacteria communities that were amended with lower concentrations of triclosan (5 mg/kg and 50 mg/kg) initially diverged and then reconverged with the control community structure. Methane production at 500 mg/kg was nearly half the methane production in control cultures. At 50 mg/kg, a large variability in methane production was observed, suggesting that 50 mg/kg may be a tipping point where function begins to fail in some communities. When previously unexposed communities were exposed to 500 mg triclosan/kg, function was maintained, but the abundance of a gene encoding for triclosan resistance (mexB) increased. This research suggests that triclosan could inhibit methane production in anaerobic digesters if concentrations were to increase and may also select for resistant Bacteria. In both cases, microbial community composition and exposure history alter the influence of triclosan.

  6. Multilevel spatial structure impacts on the pollination services of Comarum palustre (Rosaceae.

    Directory of Open Access Journals (Sweden)

    Laurent Somme

    Full Text Available Habitat destruction and fragmentation accelerate pollinator decline, consequently disrupting ecosystem processes such as pollination. To date, the impacts of multilevel spatial structure on pollination services have rarely been addressed. We focused on the effects of population spatial structure on the pollination services of Comarum palustre at three levels (i.e. within-population, between-populations and landscape. For three years, we investigated 14 Belgian populations, which differed in their within-population flower density, population surface, closure (i.e. proportion of the population edge that consisted of woody elements and isolation (i.e. percentage of woody area cover within a 500 m radius from the population centre. We tested whether these spatial characteristics impact on pollinator abundance and visitation rate and thus, reproductive success of C. palustre. Insects were observed in 15 randomly-chosen plots in each population. We tested for pollen limitation with supplemental hand-cross pollination. Bumble bees and solitary bees were the major pollinators through all populations. Within populations, plots with high flower densities attracted high numbers of bumble bees and other insects. High bumble bee and solitary bee abundance was observed in populations presenting high proportions of woody edges and in populations within landscapes presenting high proportions of woody areas. Seed set resulting from open pollination varied with bumble bee and solitary bee visitation rate, leading to increased pollen limitation when pollinators were scarce. Since the reproductive success depended on the visitation rate of the main pollinators, which depended on multilevel spatial structure, wetland management plans should pay special attention to favour a mosaic of biotopes, including nesting sites and food resources for insects. This study particularly supports the relevance of a mix wetlands and woody habitats to bees.

  7. The Beaverhead impact structure, SW Montana and Idaho: Implications for the regional geology of the western U.S.

    Energy Technology Data Exchange (ETDEWEB)

    Fiske, P.S.; Hargaves, R.B.

    1994-03-17

    The Beaverhead impact structure in SW Montana and Idaho is an allochthonous fragment of a large impact structure ({approximately} 100 km diameter) that was transported some distance eastward during the Cretaceous Sevier orogeny. It is the first tectonic fragment of a large impact structure identified in the geologic record. The present evidence for impact consists of shatter cones, pseudotachylites, and planar deformation features in quartz. The age of the impact is not well constrained but is estimated to be Neoproterozoic to Cambrian (1000-500 Ma). The Beaverhead impact event must have created other features that may be preserved, elsewhere in western Montana and Idaho. These include proximal and distal ejecta (which may be misinterpreted as diamictites and/or tuff horizons) and other fragments of the crater floor containing shatter cones and pseudotachylite. A large circular gravity, magnetic and topographic anomaly, which could be the root of the impact structure, has been identified near Challis, Idaho. An enigmatic lithic tuff, identified in drill cores from the Challis area and an intraformational quartzite breccia in the Leaton Gulch area may be impact-related deposits, but no definitive evidence of shock metamorphism has been observed in these materials. The discovery of more pieces of the Beaverhead puzzle, as well as the recognition of other large impacts in the geologic record, are likely once the regional geologic community grows to accept the incidence of such events and becomes more familiar with the features of shock metamorphism in the field. To that end, the community of geologists in this area should integrate the Beaverhead structure into their research and teaching curriculum.

  8. X-rays in protoplanetary disks: their impact on the thermal and chemical structure, a grid of models.

    NARCIS (Netherlands)

    Aresu, G.; Kamp, I.; Meijerink, R.; Woitke, P.; Thi, W. F.; Spaans, M.

    2011-01-01

    X-rays impact protoplanetary disks hydrostatic, thermal and chemical structure. The range of efficiency of X-rays is explored using a grid modelling approach: different parameters affects the structure of the disk, this determines different contribution of the X-ray radiation to the chemistry and th

  9. X-rays in protoplanetary disks : Their impact on the thermal and chemical structure, a grid of models

    NARCIS (Netherlands)

    Aresu, G.; Kamp, I.; Meijerink, R.; Woitke, P.; Thi, W. F.; Spaans, M.C.

    2011-01-01

    X-rays impact protoplanetary disks hydrostatic, thermal and chemical structure. The range of efficiency of X-rays is explored using a grid modelling approach: different parameters affects the structure of the disk, this determines different contribution of the X-ray radiation to the chemistry and th

  10. Probing the Impact of Local Structural Dynamics of Conformational Epitopes on Antibody Recognition.

    Science.gov (United States)

    Liang, Yu; Guttman, Miklos; Davenport, Thaddeus M; Hu, Shiu-Lok; Lee, Kelly K

    2016-04-19

    Antibody-antigen interactions are governed by recognition of specific residues and structural complementarity between the antigen epitope and antibody paratope. While X-ray crystallography has provided detailed insights into static conformations of antibody-antigen complexes, factors such as conformational flexibility and dynamics, which are not readily apparent in the structures, can also have an impact on the binding event. Here we investigate the contribution of dynamics in the HIV-1 gp120 glycoprotein to antibody recognition of conserved conformational epitopes, including the CD4- and coreceptor-binding sites, and an inner domain site that is targeted by ADCC-active antibodies. Hydrogen/deuterium-exchange mass spectrometry (HDX-MS) was used to measure local structural dynamics across a panel of variable loop truncation mutants of HIV-1 gp120, including full-length gp120, ΔV3, ΔV1/V2, and extended core, which includes ΔV1/V2 and V3 loop truncations. CD4-bound full-length gp120 was also examined as a reference state. HDX-MS revealed a clear trend toward an increased level of order of the conserved subunit core resulting from loop truncation. Combined with biolayer interferometry and enzyme-linked immunosorbent assay measurements of antibody-antigen binding, we demonstrate that an increased level of ordering of the subunit core was associated with better recognition by an array of antibodies targeting complex conformational epitopes. These results provide detailed insight into the influence of structural dynamics on antibody-antigen interactions and suggest the importance of characterizing the structural stability of vaccine candidates to improve antibody recognition of complex epitopes.

  11. Impact of Interfacial Characteristics on Foam Structure: Study on Model Fluids and at Pilot Scale

    Directory of Open Access Journals (Sweden)

    Mezdour Samir

    2017-03-01

    Full Text Available Foams represent an important area of research because of their relevance to many industrial processes. In continuous foaming operations, foaming ability depends on the process parameters and the characteristics of the raw materials used for foamed products. The effects of fluid viscosity and equilibrium surface tension on foam structure have been studied extensively. Furthermore, as surface active agents diffuse to the interface, they can modify other interface properties through their adsorption, such as interfacial rheology and surface tension kinetics. In order to better understand how these two interfacial properties influence foam structuring, we formulated model foaming solutions with different interface viscoelasticity levels and adsorption rates, but all with the same equilibrium surface tension and viscosity. The solutions were made up of a surface active agent and glucose syrup, so as to maintain a Newtonian behaviour. Five surface active agents were used: Whey Protein Isolate (WPI, sodium caseinate, saponin, cetyl phosphate and Sodium Dodecyl Sulphate (SDS, at concentrations ranging from 0.1% to 1%. Their molecular characteristics, and their interaction with the glucose syrup, made it possible to obtain a range of interface viscoelasticities and surface tension kinetics for these model solutions. The solutions were whipped in a continuously-operating industrial foaming device in order to control process parameters such as shearing and overrun, and to ensure that the experiment was representative of industrial production. The structure of the foams thus obtained foams was then determined by characterising bubble size using image analysis. For all the model solutions, both the viscoelastic moduli and apparent diffusion coefficient were linked to foam structure. The results showed that both high interface viscoelasticity and rapid diffusion kinetics induced a foam structure containing small bubbles. Both effects, as well as the impact of

  12. Impact of Atomic Structure on Absolute Energy Levels of Methylammonium Lead Iodide Perovskite

    Science.gov (United States)

    Choi, Joshua

    2015-03-01

    There has been a staggeringly rapid increase in the photovoltaic performance of methylammonium lead iodide (MAPbI3) perovskite - greater than 19 percent solar cell power conversion efficiency has been reported in less than five years since the first report in 2009. Despite the progress in device performance, structure-property relationships in MAPbI3 are still poorly understood. I will present our recent findings on the impact of changing the Pb-I bond length and Pb-I-Pb bond angle on the electronic structure of MAPbI3. By using the combination of temperature dependent X-ray scattering, ultraviolet photoelectron spectroscopy, absorbance and PL spectroscopy, we show that the energy levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) shift in the same direction as MAPbI3 goes through tetragonal-to-cubic structural phase transition wherein the rotational angle of PbI6 octahedra is the order parameter of the transition. Our experimental results are corroborated by density functional theory calculations which show that the lattice expansion and bond angle distortion cause different degree of orbital overlap between the Pb and I atoms and the anti-bonding orbital nature of both HOMO and LUMO results in the same direction of their shift. Moreover, through pair distribution function analysis of X-ray scattering, we discovered that the majority of MAPbI3 in thin film solar cell layer has highly disordered structure with a coherence range of only 1.4 nm. The nanostructuring correlates with a blueshift of the absorption onset and increases the photoluminescence. Our results underscore the importance of understanding the structure-property relationships in order to improve the device performance of metal-organic perovskites.

  13. Numerical modeling of the dynamic behavior of structures under impact with a discrete elements / finite elements coupling; Modelisation numerique du comportement dynamique de structures sous impact severe avec un couplage elements discrets / elements finis

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, J.

    2009-07-15

    That study focuses on concrete structures submitted to impact loading and is aimed at predicting local damage in the vicinity of an impact zone as well as the global response of the structure. The Discrete Element Method (DEM) seems particularly well suited in this context for modeling fractures. An identification process of DEM material parameters from macroscopic data (Young's modulus, compressive and tensile strength, fracture energy, etc.) will first be presented for the purpose of enhancing reproducibility and reliability of the simulation results with DE samples of various sizes. Then, a particular interaction, between concrete and steel elements, was developed for the simulation of reinforced concrete. The discrete elements method was validated on quasi-static and dynamic tests carried out on small samples of concrete and reinforced concrete. Finally, discrete elements were used to simulate impacts on reinforced concrete slabs in order to confront the results with experimental tests. The modeling of a large structure by means of DEM may lead to prohibitive computation times. A refined discretization becomes required in the vicinity of the impact, while the structure may be modeled using a coarse FE mesh further from the impact area, where the material behaves elastically. A coupled discrete-finite element approach is thus proposed: the impact zone is modeled by means of DE and elastic FE are used on the rest of the structure. An existing method for 3D finite elements was extended to shells. This new method was then validated on many quasi-static and dynamic tests. The proposed approach is then applied to an impact on a concrete structure in order to validate the coupled method and compare computation times. (author)

  14. Beginning elementary school teachers' perceptions of structural and cultural context factors impacting their science teaching

    Science.gov (United States)

    Sterling, Hillary A.

    Science maintains low status in many elementary classrooms. Beginning teachers find it difficult to teach science effectively. The Teacher-Centered Systemic Reform Model suggests there are personal, structural, and cultural factors that impact teaching practices. The questions that drove this study were: (a) How do beginning teachers perceive structural and cultural factors of the TCSR model as affecting their science teaching practices? (b) How do those perceptions compare between beginning teachers who teach science and those who do not? (c) How do beginning teachers' perceptions compare to those of principals and veteran teachers? The model was used to collect and analyze data on the perceptions of factors that influenced beginning teachers' science teaching practices. A case study involved six beginning teachers from three elementary schools in the southwestern United States during the 2005--2006 school year. Through an initial survey, two groups of beginning teachers were first identified as (a) those who taught and liked science, and (b) those who did not teach or like science. Three teachers from each group were selected to participate in the study that consisted of semi-structured interviews, observations, and review of artifacts. These data were compared with interview data from three veteran teachers and three principals. The findings of this study supported the TCSR model and confirmed that the beginning teachers did perceive certain structural context factors (e.g., curriculum, materials, time, professional development, district requirements, classroom management), and cultural context factors (e.g., district-wide low priority of science) as having an impact on their science teaching. The veteran teachers' perceptions more closely matched those of the beginning teachers' than did those of the principals. Despite the contextual influences, the beginning teachers' perceptions ultimately differed in teacher thinking (i.e., those who taught science had

  15. Probing the Impact of the EchinT C-Terminal Domain on Structure and Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    S Bardaweel; J Pace; T Chou; V Cody; C Wagner

    2011-12-31

    Histidine triad nucleotide binding protein (Hint) is considered as the ancestor of the histidine triad protein superfamily and is highly conserved from bacteria to humans. Prokaryote genomes, including a wide array of both Gram-negative bacteria and Gram-positive bacteria, typically encode one Hint gene. The cellular function of Hint and the rationale for its evolutionary conservation in bacteria have remained a mystery. Despite its ubiquity and high sequence similarity to eukaryote Hint1 [Escherichia coli Hint (echinT) is 48% identical with human Hint1], prokaryote Hint has been reported in only a few studies. Here we report the first conformational information on the full-length N-terminal and C-terminal residues of Hint from the E. coli complex with GMP. Structural analysis of the echinT-GMP complex reveals that it crystallizes in the monoclinic space group P2{sub 1} with four homodimers in the asymmetric unit. Analysis of electron density for both the N-terminal residues and the C-terminal residues of the echinT-GMP complex indicates that the loops in some monomers can adopt more than one conformation. The observation of conformational flexibility in terminal loop regions could explain the presence of multiple homodimers in the asymmetric unit of this structure. To explore the impact of the echinT C-terminus on protein structure and catalysis, we conducted a series of catalytic radiolabeling and kinetic experiments on the C-terminal deletion mutants of echinT. In this study, we show that sequential deletion of the C-terminus likely has no effect on homodimerization and a modest effect on the secondary structure of echinT. However, we observed a significant impact on the folding structure, as reflected by a significant lowering of the T{sub m} value. Kinetic analysis reveals that the C-terminal deletion mutants are within an order of magnitude less efficient in catalysis compared to wild type, while the overall kinetic mechanism that proceeds through a fast step

  16. Environmental impact assessment of structural flood mitigation measures by a rapid impact assessment matrix (RIAM) technique: a case study in Metro Manila, Philippines.

    Science.gov (United States)

    Gilbuena, Romeo; Kawamura, Akira; Medina, Reynaldo; Amaguchi, Hideo; Nakagawa, Naoko; Bui, Duong Du

    2013-07-01

    In recent decades, the practice of environmental impact assessment (EIA) in the planning processes of infrastructure projects has created significant awareness on the benefits of environmentally sound and sustainable urban development around the world. In the highly urbanized megacities in the Philippines, like Metro Manila, high priority is given by the national government to structural flood mitigation measures (SFMM) due to the persistently high frequency of flood-related disasters, which are exacerbated by the on-going effects of climate change. EIA thus, should be carefully and effectively executed to maximize the potential benefits of the SFMM. The common practice of EIA in the Philippines is generally qualitative and lacks clear methodology in evaluating multi-criteria systems. Thus, this study proposes the use of the rapid impact assessment matrix (RIAM) technique to provide a method that would systematically and quantitatively evaluate the socio-economic and environmental impacts of planned SFMM in Metro Manila. The RIAM technique was slightly modified to fit the requirements of this study. The scale of impact was determined for each perceived impact, and based on the results, the planned SFMM for Metro Manila will likely bring significant benefits; however, significant negative impacts may also likely occur. The proposed modifications were found to be highly compatible with RIAM, and the results of the RIAM analysis provided a clear view of the impacts associated with the implementation of SFMM projects. This may prove to be valuable in the practice of EIA in the Philippines.

  17. Codon optimization of the adenoviral fiber negatively impacts structural protein expression and viral fitness

    Science.gov (United States)

    Villanueva, Eneko; Martí-Solano, Maria; Fillat, Cristina

    2016-06-01

    Codon usage adaptation of lytic viruses to their hosts is determinant for viral fitness. In this work, we analyzed the codon usage of adenoviral proteins by principal component analysis and assessed their codon adaptation to the host. We observed a general clustering of adenoviral proteins according to their function. However, there was a significant variation in the codon preference between the host-interacting fiber protein and the rest of structural late phase proteins, with a non-optimal codon usage of the fiber. To understand the impact of codon bias in the fiber, we optimized the Adenovirus-5 fiber to the codon usage of the hexon structural protein. The optimized fiber displayed increased expression in a non-viral context. However, infection with adenoviruses containing the optimized fiber resulted in decreased expression of the fiber and of wild-type structural proteins. Consequently, this led to a drastic reduction in viral release. The insertion of an exogenous optimized protein as a late gene in the adenovirus with the optimized fiber further interfered with viral fitness. These results highlight the importance of balancing codon usage in viral proteins to adequately exploit cellular resources for efficient infection and open new opportunities to regulate viral fitness for virotherapy and vaccine development.

  18. Impact of network structure and cellular response on spike time correlations.

    Directory of Open Access Journals (Sweden)

    James Trousdale

    Full Text Available Novel experimental techniques reveal the simultaneous activity of larger and larger numbers of neurons. As a result there is increasing interest in the structure of cooperative--or correlated--activity in neural populations, and in the possible impact of such correlations on the neural code. A fundamental theoretical challenge is to understand how the architecture of network connectivity along with the dynamical properties of single cells shape the magnitude and timescale of correlations. We provide a general approach to this problem by extending prior techniques based on linear response theory. We consider networks of general integrate-and-fire cells with arbitrary architecture, and provide explicit expressions for the approximate cross-correlation between constituent cells. These correlations depend strongly on the operating point (input mean and variance of the neurons, even when connectivity is fixed. Moreover, the approximations admit an expansion in powers of the matrices that describe the network architecture. This expansion can be readily interpreted in terms of paths between different cells. We apply our results to large excitatory-inhibitory networks, and demonstrate first how precise balance--or lack thereof--between the strengths and timescales of excitatory and inhibitory synapses is reflected in the overall correlation structure of the network. We then derive explicit expressions for the average correlation structure in randomly connected networks. These expressions help to identify the important factors that shape coordinated neural activity in such networks.

  19. Detailed Post-Soft Impact Progressive Damage Assessment for Hybrid Structure Jet Engines

    Science.gov (United States)

    Siddens, Aaron; Bayandor, Javid; Celestina, Mark L.

    2014-01-01

    Currently, certification of engine designs for resistance to bird strike is reliant on physical tests. Predictive modeling of engine structural damage has mostly been limited to evaluation of individual forward section components, such as fan blades within a fixed frame of reference, to direct impact with a bird. Such models must be extended to include interactions among engine components under operating conditions to evaluate the full extent of engine damage. This paper presents the results of a study aim to develop a methodology for evaluating bird strike damage in advanced propulsion systems incorporating hybrid composite/metal structures. The initial degradation and failure of individual fan blades struck by a bird were investigated. Subsequent damage to other fan blades and engine components due to resultant violent fan assembly vibrations and fragmentation was further evaluated. Various modeling parameters for the bird and engine components were investigated to determine guidelines for accurately capturing initial damage and progressive failure of engine components. Then, a novel hybrid structure modeling approach was investigated and incorporated into the crashworthiness methodology. Such a tool is invaluable to the process of design, development, and certification of future advanced propulsion systems.

  20. A model of social network formation under the impact of structural balance

    Science.gov (United States)

    Li, Pei; Cheng, Jiajun; Chen, Yingwen; Wang, Hui

    2016-03-01

    Social networks have attracted remarkable attention from both academic and industrial societies and it is of great importance to understand the formation of social networks. However, most existing research cannot be applied directly to investigate social networks, where relationships are heterogeneous and structural balance is a common phenomenon. In this paper, we take both positive and negative relationships into consideration and propose a model to characterize the process of social network formation under the impact of structural balance. In this model, a new node first establishes a link with an existing node and then tries to connect to each of the newly connected node’s neighbors. If a new link is established, the type of this link is determined by structural balance. Then we analyze the degree distribution of the generated network theoretically, and estimate the fractions of positive and negative links. All analysis results are verified by simulations. These results are of importance to understand the formation of social networks, and the model can be easily extended to consider more realistic situations.

  1. Impact of Crop Rotation on Pathotype and Genetic Structure of Phythophthora sojae in Fields

    Institute of Scientific and Technical Information of China (English)

    Zhao Li-ming; Li Shuang; Sui Zhe; Huang Jing; Chen Qiu-ming; Suo Bing; Ding Jun-jie; Liu Wei-ting; Wen Jing-zhi

    2016-01-01

    To estimate the impact of crop rotation on the pathotype and genetic structure ofPhythophthora sojae in fields, 372 isolates ofP. sojae were obtained from long-term localisation experimental fields in Heilongjiang Province of China. The hypocotyl inoculation method was used to characterize the virulence ofP. sojaeon 13 differential cultivars, and the amplified fragment length polymorphism (AFLP) technique was used to analyze difference in the genetic structure ofP. sojae. The results indicated that an abundant diversity of genetic structures and pathotypes ofP. sojae, a more uniform distribution of pathotypes and less dominance of pathotypes occurred in corn-soybean and wheat-soybean rotation fields than in a continuous soybean mono-cropping field. These findings suggested thatP. sojae did not easily become the dominant race in rotation fields, which maintain disease resistance in soybean varieties. Therefore, the results of this study suggested that Phytophthora stem and root rot of soybeans could be effectively controlled by rotating soybeans with non-host crops of corn and wheat.

  2. Impact of lime, nitrogen and plant species on bacterial community structure in grassland microcosms.

    Science.gov (United States)

    Kennedy, Nabla; Brodie, Eoin; Connolly, John; Clipson, Nicholas

    2004-10-01

    A microcosm-based approach was used to study impacts of plant and chemical factors on the bacterial community structure of an upland acidic grassland soil. Seven perennial plant species typical of both natural, unimproved (Nardus stricta, Agrostis capillaris, Festuca ovina and F. rubra) and fertilized, improved (Holcus lanatus, Lolium perenne and Trifolium repens) grasslands were either left unamended or treated with lime, nitrogen, or lime plus nitrogen in a 75-day glasshouse experiment. Lime and nitrogen amendment were shown to have a greater effect on microbial activity, biomass and bacterial ribotype number than plant species. Liming increased soil pH, microbial activity and biomass, while decreasing ribotype number. Nitrogen addition decreased soil pH, microbial activity and ribotype number. Addition of lime plus nitrogen had intermediate effects, which appeared to be driven more by lime than nitrogen. Terminal restriction fragment length polymorphism (TRFLP) analysis revealed that lime and nitrogen addition altered soil bacterial community structure, while plant species had little effect. These results were further confirmed by multivariate redundancy analysis, and suggest that soil lime and nitrogen status are more important controllers of bacterial community structure than plant rhizosphere effects.

  3. In Situ Burning Restores the Ecological Function and Structure of an Oil-Impacted Coastal Marsh

    Science.gov (United States)

    Baustian, Joseph; Mendelssohn, Irving; Lin, Qianxin; Rapp, John

    2010-11-01

    As the use of in situ burning for oil spill remediation in coastal wetlands accelerates, the capacity of this procedure to restore the ecological structure and function of oil-impacted wetlands becomes increasingly important. Thus, our research focused on evaluating the functional and structural recovery of a coastal marsh in South Louisiana to an in situ burn following a Hurricane Katrina-induced oil spill. Permanent sampling plots were set up to monitor marsh recovery in the oiled and burned areas as well as non-oiled and non-burned (reference) marshes. Plots were monitored for species composition, stem density, above- and belowground productivity, marsh resiliency, soil chemistry, soil residual oil, and organic matter decomposition. The burn removed the majority of the oil from the marsh, and structurally the marsh recovered rapidly. Plant biomass and species composition returned to control levels within 9 months; however, species richness remained somewhat lower in the oiled and burned areas compared to the reference areas. Recovery of ecological function was also rapid following the in situ burn. Aboveground and belowground plant productivity recovered within one growing season, and although decomposition rates were initially higher in the oiled areas, over time they became equivalent to those in reference sites. Also, marsh resiliency, i.e., the rate of recovery from our applied disturbances, was not affected by the in situ burn. We conclude that in situ burning is an effective way to remove oil and allow ecosystem recovery in coastal marshes.

  4. Empirical Analysis of the Impact of Adjustment of Agricultural Structure on Agricultural Economic Growth in Xinjiang

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    We conduct empirical analysis of the contribution of various sectors of agriculture in Xinjiang to agricultural economic growth,and the impact of adjustment of these sectors on agricultural economic growth.The results show that the growth of farming has the greatest force to drive the growth of total agricultural output in Xinjiang,followed by animal husbandry;the rate of contribution of these two production sectors,farming and animal husbandry,not only shows high-frequency fluctuation,but also shows reverse fluctuation;the effect arising from adjustment of farming is gradually spreading to animal husbandry,forestry and fishery one by one,but the spreading rate is low.Finally the countermeasures and proposals are put forward to further adjust agricultural structure and promote agricultural economic growth of Xinjiang under the Twelfth Five-Year Plan as follows:adjust the industrial structure steadily,address the industry convergence and broaden the income-increase channels for the farmers;strengthen the input to adjustment of agricultural structure;stick to the combination of internal adjustment and external adjustment of agricultural industry.

  5. The impact of early environmental interventions on structural plasticity of the axon initial segment in neocortex.

    Science.gov (United States)

    Nozari, Masoumeh; Suzuki, Toshimitsu; Rosa, Marcello G P; Yamakawa, Kazuhiro; Atapour, Nafiseh

    2017-01-01

    Plasticity of the axon initial segment (AIS) is a newly discovered type of structural plasticity that regulates cell excitability. AIS plasticity has been reported to happen during normal development of neocortex and also in a few pathological conditions involving disruption of the inhibition/excitation balance. Here we report on the impact of early environmental interventions on structural plasticity of AIS in the mouse neocortex. C57BL/6 mice were raised in standard or enriched environment (EE) from birth up to the time of experiments and were injected with saline or MK-801 [N-Methyl-D-Aspartate (NMDA) receptor antagonist, 1 mg/kg] on postnatal days (P) 6-10. We used Ankyrin G immunoreactivity to mark the AIS of cortical neurons in two sub-regions of frontal cortex (frontal association area, FrA and secondary motor cortex, M2) and in the secondary visual cortex (V2). In 1-month-old mice, the mean AIS length differed between three areas, with the shortest AISs being observed in V2. Postnatal MK-801 or EE led to shortening of AIS only in the frontal areas. However, exposure to EE restored AIS shortening induced by MK-801. Chronic postnatal MK-801 results in structural plasticity of AIS exclusive to the frontal cortex. EE may modify underlying neuronal mechanisms resulting in restoration of AIS length. © 2016 Wiley Periodicals, Inc.

  6. The impact of liquidity on the capital structure: a case study of Croatian firms

    Directory of Open Access Journals (Sweden)

    Nataša Šarlija

    2012-01-01

    Full Text Available Background: Previous studies have shown that in some countries, liquid assets increased leverage while in other countries liquid firms were more frequently financed by their own capital and therefore were less leveraged. Objectives: The aim of this paper is to investigate the impact of liquidity on the capital structure of Croatian firms. Methods/Approach: Pearson correlation coefficient is applied to the test on the relationship between liquidity ratios and debt ratios, the share of retained earnings to capital and liquidity ratios and the relationship between the structure of current assets and leverage. Results: A survey has been conducted on a sample of 1058 Croatian firms. There are statistically significant correlations between liquidity ratios and leverage ratios. Also, there are statistically significant correlations between leverage ratios and the structure of current assets. The relationship between liquidity ratios and the short-term leverage is stronger than between liquidity ratios and the long-term leverage. Conclusions: The more liquid assets firms have, the less they are leveraged. Long- term leveraged firms are more liquid. Increasing inventory levels leads to an increase in leverage. Furthermore, increasing the cash in current assets leads to a reduction in the short-term and the long- term leverage.

  7. Elements of the Chicxulub Impact Structure as revealed in SRTM and surface GPS topographic data

    Science.gov (United States)

    Kobrick, M.; Kinsland, G. L.; Sanchez, G.; Cardador, M. H.

    2003-04-01

    Pope et al have utilized elevations from the Petroleos Mexicanos (PEMEX) gravity data files to show that the main component of the surface expression of the Chicxu-lub Impact Structure is a roughly semi-circular, low-relief depression about 90 km in diameter. They also identified other topographic features and the elements of the buried impact which possibly led to the development of these features. Kinsland et al presented a connection between these topographic anomalies, small gravity anomalies and buried structure of the impact. Shaded relief images from recently acquired SRTM elevation data clearly show the circular depression of the crater and the moat/cenote ring. In addition we can readily identify Inner trough 1, Inner trough 2 and Outer trough as defined by Pope et al. The agreement between the topographic maps of Pope et al, Kinsland et al and SRTM data are remarkable considering that the distribution and types of data in the sets are so different. We also have ground topographic data collected with a special "autonomous differ-ential GPS" system during summer 2002. Profiles from these data generally agree with both the gravity data based topographic maps and profiles extracted from the SRTM data. Preliminary analyses of our new data, SRTM and GPS, have uncovered features not previously recognized: 1) as shown by the GPS data the moat/cenote ring consists of two distinct depressions separated by about 10 km...perhaps separate ring faults, 2) in the SRTM data over the southern part of the crater and on southward for perhaps 20 km beyond the moat/ cenote ring there exists a pattern, as yet unexplained, of roughly concentric topographic features whose center lies at about 21deg 40min N and 89deg 25min W, about 50km NNE of the moat/cenote ring center. The corroboration and better definition of the previously recognized topographic features yielded by the two new forms of data strengthens the cases for these fea-tures and for their relevance to the underlying

  8. Effect of austenitizing conditions on the impact properties of an alloyed austempered ductile iron of initially ferritic matrix structure

    Energy Technology Data Exchange (ETDEWEB)

    Delia, M.; Alaalam, M.; Grech, M. [Univ. of Malta (Malta). Dept. of Metallurgy and Materials

    1998-04-01

    The effect of austenitizing conditions on the microstructure and impact properties of an austempered ductile iron (ADI) containing 1.6% Cu and 1.6% Ni as the main alloying elements was investigated. Impact tests were carried out on samples of initially ferritic matrix structure and which had been first austenitized at 850, 900, 950, and 1,000 C for 15 to 360 min and austempered at 360 C for 180 min. Results showed that the austenitizing temperature, T{sub {gamma}}, and time, t{sub {gamma}} have a significant effect on the impact properties of the alloy. This has been attributed to the influence of these variables on the carbon kinetics. Microstructures of samples austenitized at 950 and 1,000 C contain no pro-eutectoid ferrite. The impact properties of the former structures are independent of t{sub {gamma}}, while those solution treated at 1,000 C are generally low and show wide variation over the range of soaking time investigated. For fully ausferritic structures, impact properties fall with an increase in T{sub {gamma}}. This is particularly evident at 1,000 C. As the T{sub {gamma}} increases, the amount of carbon dissolved in the original austenite increases. This slows down the rate of austenite transformation and results in coarser structures with lower mechanical properties. Optimum impact properties are obtained following austenitizing between 900 and 950 C for 120 to 180 min.

  9. Earthquake impact on settlements: the role of urban and structural morphology

    Science.gov (United States)

    Bostenaru Dan, M.; Armas, I.

    2015-10-01

    This study is aimed to create an alternative to the classical GIS representation of the impact of earthquake hazards on urban areas. To accomplish this, the traditional map was revised, so that it can cope with contemporary innovative ways of planning, namely strategic planning. As in the theory of fractals, the building dimension and the urban neighbourhood dimension are addressed as different geographic scales between which lessons for decisions can be learned through regression. The interaction between the two scales is useful when looking for alternatives, for the completion of a GIS analysis, and in choosing the landmarks, which, in the case of hazards, become strategic elements in strategic planning. A methodology to innovate mapping as a digital means for analysing and visualising the impact of hazards is proposed. This method relies on concepts from various geography, urban planning, structural engineering and architecture approaches related to disaster management. The method has been tested at the building scale for the N-S Boulevard in Bucharest, Romania, called Magheru. At the urban scale, an incident database has been created, in which the case study for the building level can be mapped. The paper presented is part of a larger research work, which addresses decision making using the framework shown here. The main value of the paper is in proposing a conceptual framework to deconstruct the map for digital earthquake disaster impact analysis and representation. The originality of the concept consists in the representation of elements at different scales considered to be of different levels of importance in the urban tissue, according to the analysis to be performed on them.

  10. Wave Shaping and Lateral Spreading of Impact Loads Using Layered Materials and Structures

    Science.gov (United States)

    Ding, J. L.; Robbins, J.; Gupta, Y. M.; Wong, M. K.

    1999-06-01

    The overall objective of our work is to explore a new concept for developing resilient armor using high wave speed layers to rapidly spread the loads arising from projectile impacts. Because layered structures involve many additional geometrical and material variables, and because layers affect stress distribution and energy absorption capability of the target, a fundamental issue in determining layering effects is the quantification of load spreading in a consistent manner. We have found that the distribution of dissipative energy density normalized by the averaged total energy density imparted to the substrate appears to be an effective measure for evaluating load spreading and penetration resistance of layered targets. Using this measure in numerical simulations, we have demonstrated the feasibility of the load spreading concept. In addition, we have also investigated numerically the effects of layering geometry, and mechanical properties of the layer and substrate on load spreading. Experimental work is currently underway to evaluate the computational results.

  11. The Impact of Force Structures and the Army on Maintaining the Regime in Belarus

    Directory of Open Access Journals (Sweden)

    Neliupšienė Jovita

    2014-12-01

    Full Text Available The article analyzes how the army and other Belarusian institutions constituting the architecture of security can make an impact on the stability of the regime. Two problematic issues are raised. The first issue deals with how the force structure system and its formal and informal control, management and definition of short-and medium-term functions determine the stability of the Belarusian regime. The second issue poses the question whether the centralization of internal and army management, definition of control and functions is the decisive factor or militarization. Attention is paid to institutional analysis. Attempts are made to reveal how and why functions of the army and security institutions are defined, which of them are formal and which are informal, and what informal institutions or organizations contribute to the efforts of formal institutions to ensure the stability of the regime.

  12. Impact Characteristic According to the Structure of Crash Box at the Vehicle

    Directory of Open Access Journals (Sweden)

    Min B.S.

    2017-06-01

    Full Text Available The crash box between a bumper and a car body in automobiles can reduce impacts for car bodies with a bumper at a low-speed collision by preventing the shocks. Also, this crash box is the part playing a very important role for the safety of vehicle and the reduction of repair cost, and many studies have been investigated for the performance. In this study, aluminum foam was inserted in an aluminum crash box to analyze the relationships of deformation, stress and internal energy. The compression characteristics are compared with six cases. In addition, the load due to displacement at experiment for a case is verified by modeling with finite elements and performing the structural analysis. As these study results for investigating characteristics of the crash box, it is thought that the effective designs of crash box to enhance the durability for collision are made possible.

  13. Impact of the antimicrobial peptide Novicidin on membrane structure and integrity

    DEFF Research Database (Denmark)

    Nielsen, Søren B; Otzen, Daniel Erik

    2010-01-01

    We have studied the impact of an 18-residue cationic antimicrobial peptide Novicidin (Nc) on the structure and integrity of partially anionic lipid membranes using oriented circular dichroism (OCD), quartz crystal microbalance with dissipation (QCM-D), dual polarization interferometry (DPI...... fluorescence spectroscopy and by loss of lipid alignment in DPI analysis. Laurdan generalized polarity shows a decrease in water accessibility or mobility in the hydrophobic/hydrophilic interface of the lipid membrane, consistent with rearrangement of lipid packing. QCM-D studies on the interaction of Nc...... with lipid membranes emphasize the importance of including the dissipation factor in data analysis, revealing formation of a highly hydrated film after exposure to 3muMNc. Our findings suggest a carpet mechanism of membrane disruption in which peptide binding first induces leakage at a critical surface...

  14. The Impact of the 2008 Crisis on BM&FBovespa’s Term Structure of Conditional Correlations

    Directory of Open Access Journals (Sweden)

    Mauro Mastella

    2014-05-01

    Full Text Available This article uses a BEKK-MGARCH model to identify the historical behavior of the term structure of covariance of the Brazilian BM&FBovespa stock exchange when compared to other exchanges in the American continent. The purpose of this research is to analyze the impact of the 2008 crisis on the cohesion of the Brazilian stock exchange when compared to the other exchanges in the sample. To this end, historical series were collected from five different stock market indexes ranging from the pre-crisis period until 2011. The bivariate modeling results indicate the presence of increased cohesion in the stock market indexes during the crisis period and the non-return of this cohesion to pre-crisis levels. They also indicate that, among the pairs analyzed, the pair of indexes IBOV x IPSA are the most appropriate choice for portfolio diversification.

  15. Impact of Ice Ages on the genetic structure of trees and shrubs.

    Science.gov (United States)

    Lascoux, Martin; Palmé, Anna E; Cheddadi, Rachid; Latta, Robert G

    2004-02-29

    Data on the genetic structure of tree and shrub populations on the continental scale have accumulated dramatically over the past decade. However, our ability to make inferences on the impact of the last ice age still depends crucially on the availability of informative palaeoecological data. This is well illustrated by the results from a recent project, during which new pollen fossil maps were established and the variation in chloroplast DNA was studied in 22 European species of trees and shrubs. Species exhibit very different levels of genetic variation between and within populations, and obviously went through very different histories after Ice Ages. However, when palaeoecological data are non-informative, inferences on past history are difficult to draw from entirely genetic data. On the other hand, as illustrated by a study in ponderosa pine, when we can infer the species' history with some certainty, coalescent simulations can be used and new hypotheses can be tested.

  16. Vibration measurement through high speed vision system in a civil structure under impact loading

    Science.gov (United States)

    Ferrer, Belén; García, Juan I.; Roig, Ana B.; Mas, David

    2014-05-01

    The method presented in this work is a simple, cheap and non-contact method. It is based on image processing using a circular target. It has subpixel accuracy and it only needs a low cost high-speed camera and a tripod. In the work presented in this paper, a Casio Exilim camera was used to measure the vibration of a pedestrian bridge. An impact load was applied on the bridge through one person jumping in the middle of the bridge. Tracking of the circle border give the center trajectory and therefore the displacement and frequency of the movement. Some accelerometers were used as a contrast device for the frequency. The displacement obtained by our procedure was previously checked in laboratory using a micrometric bench. The results show that this method is suitable for measuring successfully the vibration of civil structures.

  17. Impact of Insertion Sequences and Recombination on the Population Structure of Staphylococcus haemolyticus.

    Directory of Open Access Journals (Sweden)

    Ons Bouchami

    Full Text Available Staphylococcus haemolyticus is one of the most common pathogens associated with medical-device related infections, but its molecular epidemiology is poorly explored. In the current study, we aimed to better understand the genetic mechanisms contributing to S. haemolyticus diversity in the hospital environment and their impact on the population structure and clinical relevant phenotypic traits. The analysis of a representative S. haemolyticus collection by multilocus sequence typing (MLST has identified a single highly prevalent and diverse genetic lineage of nosocomial S. haemolyticus clonal complex (CC 29 accounting for 91% of the collection of isolates disseminated worldwide. The examination of the sequence changes at MLST loci during clonal diversification showed that recombination had a higher impact than mutation in shaping the S. haemolyticus population. Also, we ascertained that another mechanism contributing significantly to clonal diversification and adaptation was mediated by insertion sequence (IS elements. We found that all nosocomial S. haemolyticus, belonging to different STs, were rich in IS1272 copies, as determined by Southern hybridization of macrorestriction patterns. In particular, we observed that the chromosome of a S. haemolyticus strain within CC29 was highly unstable during serial growth in vitro which paralleled with IS1272 transposition events and changes in clinically relevant phenotypic traits namely, mannitol fermentation, susceptibility to beta-lactams, biofilm formation and hemolysis. Our results suggest that recombination and IS transposition might be a strategy of adaptation, evolution and pathogenicity of the major S. haemolyticus prevalent lineage in the hospital environment.

  18. The impact of culture and employee-focused criteria on productivity: A structural equation modelling approach

    Science.gov (United States)

    Ab Hamid, Mohd Rashid; Mustafa, Zainol; Mohd Suradi, Nur Riza; Idris, Fazli; Abdullah, Mokhtar

    2013-04-01

    Culture and employee-focused criteria are important factors for the success of any organization. These factors have to be aligned with the productivity initiatives in the organization in order to gear ahead for excellence. Therefore, this article investigated the impact of culture and employee-focused criteria on productivity in Higher Education Institutions (HEIs) in Malaysia using intangible indicators through core values. The hypothesized relationship was tested using Structural Equation Modeling (SEM) with the PLS estimation technique. 429 questionnaires were returned from the target population. The results of the modelling revealed that the PLS estimation confirmed all the hypotheses tested as in the hypothesized model. The results generally support significant relationships between culture values, employee-focused values and productivity-focused values. The study also confirmed the mediating role of employee-focused values for the relationship between culture values and productivity-focused values. In conclusion, the empirically validated results supported the adequacy of the hypothezised model of the impact of culture and employee-focused criteria on productivity in HEI through value-based indicators.

  19. Temperature impact on the micro structure of tungsten exposed to He irradiation in LHD

    Science.gov (United States)

    Bernard, Elodie; Sakamoto, Ryuichi; Tokitani, Masayuki; Masuzaki, Suguru; Hayashi, Hiromi; Yamada, Hiroshi; Yoshida, Naoaki

    2017-02-01

    A new temperature controlled material probe was designed for the exposure of tungsten samples to helium plasma in the LHD. Samples were exposed to estimated fluences of ∼1023 m-2 and temperatures ranging from 65 to 600 °C. Transmission Electron Microscopy analysis allowed the study of the impact of He irradiation under high temperatures on tungsten micro structure for the first time in real-plasma exposure conditions. Both dislocation loops and bubbles appeared from low to medium temperatures and saw an impressive increase of size (factor 4 to 6) most probably by coalescence as the temperature reaches 600 °C, with 500 °C appearing as a threshold for bubble growth. Annealing of the samples up to 800 C highlighted the stability of the dislocation damages formed by helium irradiation at high surface temperature, as bubbles and dislocation loops seem to conserve their characteristics. Additional studies on cross-sections showed that bubbles were formed much deeper (70-100 nm) than the heavily damaged surface layer (10-20 nm), raising concern about the impact on the material mechanical properties conservation and potential additional trapping of hydrogen isotopes.

  20. Hyperspectral mapping of alteration assemblages within a hydrothermal vug at the Haughton impact structure, Canada

    Science.gov (United States)

    Greenberger, Rebecca N.; Mustard, John F.; Osinski, Gordon R.; Tornabene, Livio L.; Pontefract, Alexandra J.; Marion, Cassandra L.; Flemming, Roberta L.; Wilson, Janette H.; Cloutis, Edward A.

    2016-12-01

    Meteorite impacts on Earth and Mars can generate hydrothermal systems that alter the primary mineralogies of rocks and provide suitable environments for microbial colonization. We investigate a calcite-marcasite-bearing vug at the 23 km diameter Haughton impact structure, Devon Island, Nunavut, Canada, using imaging spectroscopy of the outcrop in the field (0.65-1.1 μm) and samples in the laboratory (0.4-2.5 μm), point spectroscopy (0.35-2.5 μm), major element chemistry, and X-ray diffraction analyses. The mineral assemblages mapped at the outcrop include marcasite; marcasite with minor gypsum and jarosite; fibroferrite and copiapite with minor gypsum and melanterite; gypsum, Fe3+ oxides, and jarosite; and calcite, gypsum, clay, microcline, and quartz. Hyperspectral mapping of alteration phases shows spatial patterns that illuminate changes in alteration conditions and formation of specific mineral phases. Marcasite formed from the postimpact hydrothermal system under reducing conditions, while subsequent weathering oxidized the marcasite at low temperatures and water/rock ratios. The acidic fluids resulting from the oxidation collected on flat-lying portions of the outcrop, precipitating fibroferrite + copiapite. That assemblage then likely dissolved, and the changing chemistry and pH resulting from interaction with the calcite-rich host rock formed gypsum-bearing red coatings. These results have implications for understanding water-rock interactions and habitabilities at this site and on Mars.

  1. Impact of Backbone Tether Length and Structure on the Electrochemical Performance of Viologen Redox Active Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, Mark; Chénard, Etienne; Hernández-Burgos, Kenneth; Nagarjuna, Gavvalapalli; Assary, Rajeev S.; Hui, Jingshu; Moore, Jeffrey S.; Rodríguez-López, Joaquín

    2016-10-25

    The design of chemically stable and electrochemically reversible redox active polymers (RAPs) is of great interest for energy storage technologies. Particularly, RAPs are new players for flow batteries relying on a size-exclusion based mechanism of electrolyte separation, but few studies have provided detailed molecular understanding of redox polymers in solution. Here, we use a systematic molecular design approach to investigate the impact of linker and redox-pendant electronic interactions on the performance of viologen RAPs. We used scanning electrochemical microscopy, cyclic voltammetry, bulk electrolysis, temperature-dependent absorbance, and spectroelectrochemistry to study the redox properties, charge transfer kinetics, and self-exchange of electrons through redox active dimers and their equivalent polymers. Stark contrast was observed between the electrochemical properties of viologen dimers and their corresponding polymers. Electron self-exchange kinetics in redox active dimers that only differ by their tether length and rigidity influences their charge transfer properties. Predictions from the Marcus Hush theory were consistent with observations in redox active dimers, but they failed to fully capture the behavior of macromolecular systems. For example, polymer bound viologen pendants, if too close in proximity, do not retain chemical reversibility. In contrast to polymer films, small modifications to the backbone structure decisively impact the bulk electrolysis of polymer solutions. This first comprehensive study highlights the careful balance between electronic interactions and backbone rigidity required to design RAPs with superior electrochemical performance.

  2. Dalcetrapib and anacetrapib differently impact HDL structure and function in rabbits and monkeys.

    Science.gov (United States)

    Brodeur, Mathieu R; Rhainds, David; Charpentier, Daniel; Mihalache-Avram, Teodora; Mecteau, Mélanie; Brand, Geneviève; Chaput, Evelyne; Perez, Anne; Niesor, Eric J; Rhéaume, Eric; Maugeais, Cyrille; Tardif, Jean-Claude

    2017-07-01

    Inhibition of cholesteryl ester transfer protein (CETP) increases HDL cholesterol (HDL-C) levels. However, the circulating CETP level varies and the impact of its inhibition in species with high CETP levels on HDL structure and function remains poorly characterized. This study investigated the effects of dalcetrapib and anacetrapib, the two CETP inhibitors (CETPis) currently being tested in large clinical outcome trials, on HDL particle subclass distribution and cholesterol efflux capacity of serum in rabbits and monkeys. New Zealand White rabbits and vervet monkeys received dalcetrapib and anacetrapib. In rabbits, CETPis increased HDL-C, raised small and large α-migrating HDL, and increased ABCA1-induced cholesterol efflux. In vervet monkeys, although anacetrapib produced similar results, dalcetrapib caused opposite effects because the LDL-C level was increased by 42% and HDL-C decreased by 48% (P HDL were reduced by 16% (P HDL in vivo and consequently the cholesterol efflux capacity. The opposite effects of dalcetrapib in different species indicate that its impact on HDL metabolism could vary greatly according to the metabolic environment. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

  3. Impact of the Fused Deposition (FDM Printing Process on Polylactic Acid (PLA Chemistry and Structure

    Directory of Open Access Journals (Sweden)

    Michael Arthur Cuiffo

    2017-06-01

    Full Text Available Polylactic acid (PLA is an organic polymer commonly used in fused deposition (FDM printing and biomedical scaffolding that is biocompatible and immunologically inert. However, variations in source material quality and chemistry make it necessary to characterize the filament and determine potential changes in chemistry occurring as a result of the FDM process. We used several spectroscopic techniques, including laser confocal microscopy, Fourier transform infrared (FTIR spectroscopy and photoacousitc FTIR spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS in order to characterize both the bulk and surface chemistry of the source material and printed samples. Scanning electron microscopy (SEM and differential scanning calorimetry (DSC were used to characterize morphology, cold crystallinity, and the glass transition and melting temperatures following printing. Analysis revealed calcium carbonate-based additives which were reacted with organic ligands and potentially trace metal impurities, both before and following printing. These additives became concentrated in voids in the printed structure. This finding is important for biomedical applications as carbonate will impact subsequent cell growth on printed tissue scaffolds. Results of chemical analysis also provided evidence of the hygroscopic nature of the source material and oxidation of the printed surface, and SEM imaging revealed micro- and submicron-scale roughness that will also impact potential applications.

  4. Windpower project ownership and financing: The cost impacts of alternative development structures

    Energy Technology Data Exchange (ETDEWEB)

    Wiser, R.H. [Lawrence Berkeley National Lab., CA (United States)

    1997-12-31

    This paper uses traditional financial cash-flow techniques to examine the impact of different ownership and financing structures on the cost of wind energy. While most large-scale wind projects are constructed, operated, and financed by non-utility generators (NUGs) via project financing, investor- and publicly-owned utilities have expressed interest in owning and financing their own facilities rather than purchasing wind energy from independent generators. A primary justification for utility ownership is that, because of financing and tax benefits, windpower may be cheaper when developed in this fashion. The results presented in this paper support that justification, though some of the estimated cost savings associated with utility ownership are found to be a result of shortcomings in utility analysis procedures and implicit risk shifting. This paper also discusses the comparative value of the federal production tax credit and renewable energy production incentive; estimates the financing premium paid by NUG wind owners compared to traditional gas-fired generation facilities; and explores the impact of electricity restructuring on financing.

  5. Impact of model structure and parameterization on Penman-Monteith type evaporation models

    KAUST Repository

    Ershadi, A.

    2015-04-12

    The impact of model structure and parameterization on the estimation of evaporation is investigated across a range of Penman-Monteith type models. To examine the role of model structure on flux retrievals, three different retrieval schemes are compared. The schemes include a traditional single-source Penman-Monteith model (Monteith, 1965), a two-layer model based on Shuttleworth and Wallace (1985) and a three-source model based on Mu et al. (2011). To assess the impact of parameterization choice on model performance, a number of commonly used formulations for aerodynamic and surface resistances were substituted into the different formulations. Model response to these changes was evaluated against data from twenty globally distributed FLUXNET towers, representing a cross-section of biomes that include grassland, cropland, shrubland, evergreen needleleaf forest and deciduous broadleaf forest. Scenarios based on 14 different combinations of model structure and parameterization were ranked based on their mean value of Nash-Sutcliffe Efficiency. Results illustrated considerable variability in model performance both within and between biome types. Indeed, no single model consistently outperformed any other when considered across all biomes. For instance, in grassland and shrubland sites, the single-source Penman-Monteith model performed the best. In croplands it was the three-source Mu model, while for evergreen needleleaf and deciduous broadleaf forests, the Shuttleworth-Wallace model rated highest. Interestingly, these top ranked scenarios all shared the simple lookup-table based surface resistance parameterization of Mu et al. (2011), while a more complex Jarvis multiplicative method for surface resistance produced lower ranked simulations. The highly ranked scenarios mostly employed a version of the Thom (1975) formulation for aerodynamic resistance that incorporated dynamic values of roughness parameters. This was true for all cases except over deciduous broadleaf

  6. Paleontological interpretations of crater processes and infilling of synimpact sediments from the Chesapeake Bay impact structure

    Science.gov (United States)

    Self-Trail, Jean M.; Edwards, Lucy E.; Litwin, Ronald J.

    2009-01-01

    Biostratigraphic analysis of sedimentary breccias and diamictons in the Chesapeake Bay impact structure provides information regarding the timing and processes of late-stage gravitational crater collapse and ocean resurge. Studies of calcareous nannofossil and palynomorph assemblages in the International Continental Scientific Drilling Program (ICDP)–U.S. Geological Survey (USGS) Eyreville A and B cores show the mixed-age, mixed-preservation microfossil assemblages that are typical of deposits from the upper part of the Chesapeake Bay impact structure. Sparse, poorly preserved, possibly thermally altered pollen is present within a gravelly sand interval below the granite slab at 1392 m in Eyreville core B, an interval that is otherwise barren of calcareous nannofossils and dinocysts. Gravitational collapse of water- saturated sediments from the transient crater wall resulted in the deposition of sediment clasts primarily derived from the nonmarine Cretaceous Potomac Formation. Collapse occurred before the arrival of resurge. Low pollen Thermal Alteration Index (TAI) values suggest that these sediments were not thermally altered by contact with the melt sheet. The arrival of resurge sedimentation is identified based on the presence of diamicton zones and stringers rich in glauconite and marine microfossils at 866.7 m. This horizon can be traced across the crater and can be used to identify gravitational collapse versus ocean-resurge sedimentation. Glauconitic quartz sand diamicton dominates the sediments above 618.2 m. Calcareous nannofossil and dino-flagellate data from this interval suggest that the earliest arriving resurge from the west contained little or no Cretaceous marine input, but later resurge pulses mined Cretaceous sediments east of the Watkins core in the annular trough. Additionally, the increased distance traveled by resurge to the central crater in turbulent flow conditions resulted in the disaggregation of Paleogene unconsolidated sediments. As

  7. Impact of a structured intern education programme on clinical documentation in the emergency department.

    Science.gov (United States)

    McLean, Andrew; Lawlor, Jenine; Mitchell, Rob; Kault, David; O'Kane, Carl; Lees, Michelle

    2015-02-01

    To evaluate the impact of More Learning for Interns in Emergency (MoLIE) on clinical documentation in the ED of a large regional hospital. MoLIE was implemented at The Townsville Hospital (TTH) in 2010, and has since provided ED interns with structured off-floor teaching and a dedicated clinical supervisor. A pre- and post-intervention study was conducted using retrospective medical record review methodology. Charts were selected by identifying all TTH ED patients seen by interns in the period 2008-2011. Two hundred pre-intervention records (2008-2009) and 200 post-intervention records (2010-2011) were reviewed. These were randomly selected following an initial screen by an ED staff specialist. The quality of clinical documentation for five common ED presentations (asthma, chest pain, lacerations, abdominal pain and upper limb fractures) was assessed. For each presentation, documentation quality was scored out of 10 using predefined criteria. An improvement of two or more was thought to be clinically significant. Mean scores for each group were compared using a Student's t-test for independent samples. Mean documentation scores (and 95% confidence intervals) were 5.55 (5.17-5.93) in 2008, 5.42 (4.98-5.86) in 2009, 6.37 (5.99-6.75) in 2010 and 6.08 (5.71-6.45) in 2011. There was a statistically but not clinically significant improvement in scores pre- and post-intervention (P ≤ 0.001). The introduction of MoLIE was associated with a small but statistically significant improvement in documentation, despite an 80% increase in intern placements. These results suggest that structured training programmes have potential to improve intern performance while simultaneously enhancing training capacity. The impact on quality of care requires further evaluation. © 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

  8. Impact of prenatal nicotine on the structure of midbrain dopamine regions in the rat.

    Science.gov (United States)

    Omelchenko, Natalia; Roy, Priya; Balcita-Pedicino, Judith Joyce; Poloyac, Samuel; Sesack, Susan R

    2016-05-01

    In utero exposure of rats to nicotine (NIC) provides a useful animal model for studying the impact of smoking during pregnancy on human offspring. Certain sequelae of prenatal NIC exposure suggest an impact on the development of the midbrain dopamine (DA) system, which receives a robust cholinergic innervation from the mesopontine tegmentum. We therefore investigated whether prenatal NIC induced structural changes in cells and synapses within the midbrain that persisted into adulthood. Osmotic minipumps delivering either sodium bitartrate (vehicle; VEH) or NIC bitartrate at 2 mg/kg/day were implanted into nine timed-pregnant dams at E4. At birth, rat pups were culled to litters of six males each, and the litters were cross-fostered. Plasma levels of NIC and cotinine from killed pups provided evidence of NIC exposure in utero. Pups separated from dams at weaning showed a trend toward reduced locomotor activity at this time point but not when tested again in adulthood. Adult rats were killed for anatomical studies. Estimates of brain size and volume did not vary with NIC treatment. Midbrain sections stained for Nissl or by immunoperoxidase for tyrosine hydroxylase and analyzed using unbiased stereology revealed no changes in volume or cell number in the substantia nigra compacta or ventral tegmental area as a result of NIC exposure. Within the ventral tegmental area, electron microscopic physical disector analysis showed no significant differences in the number of axon terminals or the number of asymmetric (putative excitatory) or symmetric (putative inhibitory) synapses. Although too infrequent to estimate by unbiased stereology, no obvious difference in the proportion of cholinergic axons was noted in NIC- versus VEH-treated animals. These data suggest that activation of nicotinic receptors during prenatal development induces no significant modifications in the structure of cells in the ventral midbrain when assessed in adulthood.

  9. Fragmentation increases wind disturbance impacts on forest structure and carbon stocks in a western Amazonian landscape.

    Science.gov (United States)

    Schwartz, Naomi B; Uriarte, María; DeFries, Ruth; Bedka, Kristopher M; Fernandes, Katia; Gutiérrez-Vélez, Victor; Pinedo-Vasquez, Miguel A

    2017-09-01

    Tropical second-growth forests could help mitigate climate change, but the degree to which their carbon potential is achieved will depend on exposure to disturbance. Wind disturbance is common in tropical forests, shaping structure, composition, and function, and influencing successional trajectories. However, little is known about the impacts of extreme winds on second-growth forests in fragmented landscapes, though these ecosystems are often located in mosaics of forest, pasture, cropland, and other land cover types. Indirect evidence suggests that fragmentation increases risk of wind damage in tropical forests, but no studies have found such impacts following severe storms. In this study, we ask whether fragmentation and forest type (old vs. second growth) were associated with variation in wind damage after a severe convective storm in a fragmented production landscape in western Amazonia. We applied linear spectral unmixing to Landsat 8 imagery from before and after the storm, and combined it with field observations of damage to map wind effects on forest structure and biomass. We also used Landsat 8 imagery to map land cover with the goals of identifying old- and second-growth forest and characterizing fragmentation. We used these data to assess variation in wind disturbance across 95,596 ha of forest, distributed over 6,110 patches. We find that fragmentation is significantly associated with wind damage, with damage severity higher at forest edges and in edgier, more isolated patches. Damage was also more severe in old-growth than in second-growth forests, but this effect was weaker than that of fragmentation. These results illustrate the importance of considering landscape context in planning tropical forest restoration and natural regeneration projects. Assessments of long-term carbon sequestration potential need to consider spatial variation in disturbance exposure. Where risk of extreme winds is high, minimizing fragmentation and isolation could increase

  10. Impact Pressure of Incident Regular Waves and Irregular Waves on the Subface of Open-Piled Structures

    Institute of Scientific and Technical Information of China (English)

    任冰; 王永学

    2004-01-01

    This paper presents the results of comparison of impact pressures on open-plied structures induced by regular waves and irregular waves in a laboratory channel. Regular waves with wave heights ranging from 0.1 ~ 0.2 m and periods ranging from 1.0 ~ 2.0 s are tested. The target spectrm for the irregular wave is JONSWAP spectrum. Irregular waves with significant wave heights in the range of 0.10 ~ 0.25 m and peak periods in the range of 1.0 ~ 2.0 s are tested. The relative clearance s/H1/3(H) is between - 0.1 and 0.4, s being the subface level of structure model above the still water level. Time series of impact pressure are analyzed to indicate whether the property of impact pressures induced by the regular wave significantly deviates from that by the irregular wave. The distribution of the impact pressure along the underside of the structure is compared for different types of incident waves. The effects of wave parameters, structure dimension and structure clearance on the impact pressure are also discussed.

  11. Impact of stock market structure on intertrade time and price dynamics.

    Directory of Open Access Journals (Sweden)

    Plamen Ch Ivanov

    Full Text Available We analyse times between consecutive transactions for a diverse group of stocks registered on the NYSE and NASDAQ markets, and we relate the dynamical properties of the intertrade times with those of the corresponding price fluctuations. We report that market structure strongly impacts the scale-invariant temporal organisation in the transaction timing of stocks, which we have observed to have long-range power-law correlations. Specifically, we find that, compared to NYSE stocks, stocks registered on the NASDAQ exhibit significantly stronger correlations in their transaction timing on scales within a trading day. Further, we find that companies that transfer from the NASDAQ to the NYSE show a reduction in the correlation strength of transaction timing on scales within a trading day, indicating influences of market structure. We also report a persistent decrease in correlation strength of intertrade times with increasing average intertrade time and with corresponding decrease in companies' market capitalization-a trend which is less pronounced for NASDAQ stocks. Surprisingly, we observe that stronger power-law correlations in intertrade times are coupled with stronger power-law correlations in absolute price returns and higher price volatility, suggesting a strong link between the dynamical properties of intertrade times and the corresponding price fluctuations over a broad range of time scales. Comparing the NYSE and NASDAQ markets, we demonstrate that the stronger correlations we find in intertrade times for NASDAQ stocks are associated with stronger correlations in absolute price returns and with higher volatility, suggesting that market structure may affect price behavior through information contained in transaction timing. These findings do not support the hypothesis of universal scaling behavior in stock dynamics that is independent of company characteristics and stock market structure. Further, our results have implications for utilising

  12. Impact of stock market structure on intertrade time and price dynamics.

    Science.gov (United States)

    Ivanov, Plamen Ch; Yuen, Ainslie; Perakakis, Pandelis

    2014-01-01

    We analyse times between consecutive transactions for a diverse group of stocks registered on the NYSE and NASDAQ markets, and we relate the dynamical properties of the intertrade times with those of the corresponding price fluctuations. We report that market structure strongly impacts the scale-invariant temporal organisation in the transaction timing of stocks, which we have observed to have long-range power-law correlations. Specifically, we find that, compared to NYSE stocks, stocks registered on the NASDAQ exhibit significantly stronger correlations in their transaction timing on scales within a trading day. Further, we find that companies that transfer from the NASDAQ to the NYSE show a reduction in the correlation strength of transaction timing on scales within a trading day, indicating influences of market structure. We also report a persistent decrease in correlation strength of intertrade times with increasing average intertrade time and with corresponding decrease in companies' market capitalization-a trend which is less pronounced for NASDAQ stocks. Surprisingly, we observe that stronger power-law correlations in intertrade times are coupled with stronger power-law correlations in absolute price returns and higher price volatility, suggesting a strong link between the dynamical properties of intertrade times and the corresponding price fluctuations over a broad range of time scales. Comparing the NYSE and NASDAQ markets, we demonstrate that the stronger correlations we find in intertrade times for NASDAQ stocks are associated with stronger correlations in absolute price returns and with higher volatility, suggesting that market structure may affect price behavior through information contained in transaction timing. These findings do not support the hypothesis of universal scaling behavior in stock dynamics that is independent of company characteristics and stock market structure. Further, our results have implications for utilising transaction timing

  13. Physico-chemical properties and cytotoxic effects of sugar-based surfactants: Impact of structural variations.

    Science.gov (United States)

    Lu, Biao; Vayssade, Muriel; Miao, Yong; Chagnault, Vincent; Grand, Eric; Wadouachi, Anne; Postel, Denis; Drelich, Audrey; Egles, Christophe; Pezron, Isabelle

    2016-09-01

    Surfactants derived from the biorefinery process can present interesting surface-active properties, low cytotoxicity, high biocompatibility and biodegradability. They are therefore considered as potential sustainable substitutes to currently used petroleum-based surfactants. To better understand and anticipate their performances, structure-property relationships need to be carefully investigated. For this reason, we applied a multidisciplinary approach to systematically explore the effect of subtle structural variations on both physico-chemical properties and biological effects. Four sugar-based surfactants, each with an eight carbon alkyl chain bound to a glucose or maltose head group by an amide linkage, were synthesized and evaluated together along with two commercially available standard surfactants. Physico-chemical properties including solubility, Krafft point, surface-tension lowering and critical micellar concentration (CMC) in water and biological medium were explored. Cytotoxicity evaluation by measuring proliferation index and metabolic activity against dermal fibroblasts showed that all surfactants studied may induce cell death at low concentrations (below their CMC). Results revealed significant differences in both physico-chemical properties and cytotoxic effects depending on molecule structural features, such as the position of the linkage on the sugar head-group, or the orientation of the amide linkage. Furthermore, the cytotoxic response increased with the reduction of surfactant CMC. This study underscores the relevance of a methodical and multidisciplinary approach that enables the consideration of surfactant solution properties when applied to biological materials. Overall, our results will contribute to a better understanding of the concomitant impact of surfactant structure at physico-chemical and biological levels.

  14. Geometries of deformed granitoid inclusions in the Sudbury Igneous Complex of the Sudbury Impact Structure, Canada: Evidence for deformation during solidification of the impact melt sheet

    Science.gov (United States)

    Lenauer, Iris; Riller, Ulrich

    2010-05-01

    The Main Mass of the 1.85 Ga Sudbury Igneous Complex (SIC) occupies the central portion of the Sudbury Impact Structure and represents an impact melt sheet that resulted from hypervelocity impact into Archaean and Proterozoic target rocks. During cooling, the ca. 3 km thick melt sheet differentiated into layers of norite, quartz gabbro and granophyre and now hosts one of the world's largest Cu-Ni-PGE deposits. Meteorite impact occurred apparently during an ongoing orogeny, i.e., the ca. 1.89 to 1.80 Ga Penokean orogeny. However, structural evidence for this is still sparse Dike-like, granitoid inclusions are exposed in the norite layer of the southern SIC. Here, sub-planar inclusions are folded and characterized by axial-planar cleavage. More specifically, fold mullions of the granitoid inclusions formed by layer-parallel NNW-SSE shortening. Cuspate-lobate geometries of the inclusion interfaces indicate that the granitoid inclusions were mechanically more competent than the norite host rock during ductile deformation of both lithologies. The contrast in mechanical strength between granitoid inclusions and norite host rock indicates ductile deformation at high temperature and low strain rates in the unconsolidated melt sheet. Shortening directions inferred from the geometry of the inclusions agree with those obtained from inversion of brittle-ductile faults from the same area, geometry of deformation in the metasedimentary strata of the Proterozoic target rocks and l-s mylonitic fabrics developed in the granophyre layer of the SIC and the overlying impact melt breccias. Collectively, these structural characteristics indicate that orogenic deformation in the Sudbury area occurred during cooling and solidification of the impact melt sheet.

  15. Impacts

    NARCIS (Netherlands)

    Hellmuth, M.; Kabat, P.

    2003-01-01

    Even without the impacts of climate change, water managers face prodigious challenges in meeting sustainable development goals. Growing populations need affordable food, water and energy. Industrial development demands a growing share of water resources and contaminates those same resources with its

  16. Impacts

    NARCIS (Netherlands)

    Hellmuth, M.; Kabat, P.

    2003-01-01

    Even without the impacts of climate change, water managers face prodigious challenges in meeting sustainable development goals. Growing populations need affordable food, water and energy. Industrial development demands a growing share of water resources and contaminates those same resources with its

  17. Consideration of hazardous and especially hazardous hydrometeorological impacts in design of buildings and structures of nuclear power plants

    Directory of Open Access Journals (Sweden)

    Bryukhan Fedor

    2016-01-01

    Full Text Available External impacts of the hydrometeorological origin have a significant influence on the safety level of objects of use of atomic energy (OUAE, including nuclear power plants (NPP. Therefore, the existing NPP-related safety regulations demand to consider such impacts at all stages of the NPP life cycle. It is important to make decisions on considering or ignoring certain external impacts while designing NPP buildings and structures. The main criterion for such decisions is the probability of a non-project accident associated with the release of radionuclides into the environment when an extreme phenomena occurs. The aim of this study is to develop a concept for refinement regulatory requirements, considering hydrometeorological factors in organization of NPP engineering protection. Criteria for consideration of hazardous and especially hazardous hydrometeorological impacts for design of NPP buildings and structures were analyzed, and recommendations for refinement of regulatory requirements, considering hydrometeorological factors in organization of NPP engineering protection, were developed.

  18. Damage evolution of composite structures at low speeds under the effect of the number of folds and impact loads

    Directory of Open Access Journals (Sweden)

    Saad Mohamed

    2016-07-01

    Full Text Available Composite materials currently occupy an important place in all industrial sectors their sensitivity to the same impacts at low velocity raises some preoccupations to limit their scope .On the basis of a numerical simulation, the code of calculation Abaqus 6.14, was used to simulate the impact behavior to predict the damage to the fibers and the matrix of the composite structures subjected to any impact. This work deals with the evolution of the damage on the individual layers of a plate composite graphite / epoxy laminated [0m / 90n ] s composite under dynamic loading effect different velocity of the impactor and the evolution of the deformation energy as a result of different speeds of impact and the various layers of the composite structure.

  19. Behavior of plywood and fiberglass steel composite tube structures subjected to impact loading

    Science.gov (United States)

    Armaghani, Seyamend Bilind

    Paratransit buses are custom built as the major vehicle manufacturer produces the custom built passenger cage installed on the chassis for the Paratransit bus. In order for these Paratransit bus members to be sufficient, they have to be evaluated for crashworthiness and energy absorption. This has prompted Florida Department of Transportation (FDOT) to fund research for the safety evaluation of Paratransit busses consisting of crash and safety analysis. There has been a large body of research done on steel subjected to static loads, but more research is needed for steel applied under dynamic loading and high speeds in order to improve crashworthiness in events such as rollovers and side impacts. Bare steel Hollow Structural Section (HSS) tubing are used a lot as structural members of Paratransit buses because of their lightness and progressive buckling under loading. The research will be conducted on quantifying the tubing's behavior under bending by conducting static three point bending and impact loading tests. In addition to the bare tubing, plywood and fiberglass composites are investigated because they are both strong and lightweight and their behavior under dynamic loading hasn't been quantified. As a result, the main purpose of this research is to quantify the differences between the dynamic and static behavior of plywood steel composite and fiberglass steel composite tubing and compare these findings with those of bare steel tubing. The differences will be quantified using detailed and thorough experiments that will examine the composites behavior under both static and dynamic loading. These tests will determine if there are any advantages of using the composite materials and thus allow for recommendations to be made to the FDOT with the goal of improving the safety of Paratransit busses. Tensile tests were conducted to determine the material properties of the tested specimens. Before the static and dynamic experiments are run to investigate the differences

  20. The impact of stellar feedback on the density and velocity structure of the interstellar medium

    Science.gov (United States)

    Grisdale, Kearn; Agertz, Oscar; Romeo, Alessandro B.; Renaud, Florent; Read, Justin I.

    2017-04-01

    We study the impact of stellar feedback in shaping the density and velocity structure of neutral hydrogen (H I) in disc galaxies. For our analysis, we carry out ∼4.6 pc resolution N-body+adaptive mesh refinement hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way and a Large and Small Magellanic Cloud. We quantify the density and velocity structure of the interstellar medium using power spectra and compare the simulated galaxies to observed H I in local spiral galaxies from THINGS (The H I Nearby Galaxy Survey). Our models with stellar feedback give an excellent match to the observed THINGS H I density power spectra. We find that kinetic energy power spectra in feedback-regulated galaxies, regardless of galaxy mass and size, show scalings in excellent agreement with supersonic turbulence (E(k) ∝ k-2) on scales below the thickness of the H I layer. We show that feedback influences the gas density field, and drives gas turbulence, up to large (kpc) scales. This is in stark contrast to density fields generated by large-scale gravity-only driven turbulence. We conclude that the neutral gas content of galaxies carries signatures of stellar feedback on all scales.

  1. Invitation choice structure has no impact on attendance in a female business training program in Kenya.

    Directory of Open Access Journals (Sweden)

    Faizan Diwan

    Full Text Available Business training programs are a common form of support to small businesses, but organizations providing this training often struggle to get business owners to attend. We evaluate the role of invitation choice structure in determining agreement to participate and actual attendance. A field experiment randomly assigned female small business owners in Kenya (N = 1172 to one of three invitation types: a standard opt-in invitation; an active choice invitation where business owners had to explicitly say yes or no to the invitation; and an enhanced active choice invitation which highlighted the costs of saying no. We find no statistically significant effect of these alternative choice structures on willingness to participate in training, attending at least one day, and completing the course. The 95 percent confidence interval for the active treatment effect on attendance is [-1.9%, +9.5%], while for the enhanced active choice treatment it is [-4.1%, +7.7%]. The effect sizes consistent with our data are smaller than impacts measured in health and retirement savings studies in the United States. We examine several potential explanations for the lack of effect in a developing country setting. We find evidence consistent with two potential reasons being limited decision-making power amongst some women, and lower levels of cognition making the enhanced active choice wording less effective.

  2. Glycation of human serum albumin in diabetes: impacts on the structure and function.

    Science.gov (United States)

    Cao, Hui; Chen, Tingting; Shi, Yujun

    2015-01-01

    Diabetes mellitus is one of the most serious diseases in the world. The levels of glycated proteins in the blood of diabetics are higher than that of non-diabetic subjects. The glycation of proteins is believed to link to the occurrence of diabetic complications and related diseases. This review focuses on the influence of glycation of human serum albumin (HSA) on its structure and function. The glycation leads to change the HSA conformation, which will further influence its ligand binding properties. The levels of glycated HSA in hyperglycemic conditions showed a significant relationship to the germination of serious complications for diabetics, especially by affecting various cells functions. The conclusion from individual report is contradictory to each other; therefore, it is very difficult to give an univocal comment on the impact of glycation on the binding behaviors of HSA for small molecules. The influence of glycation of HSA on the binding affinities for small molecules is decided by the assay, the structures of small molecules, as well as the degree of glycation. However, the glycation of HSA is believed to reduce the binding affinities for acidic drugs such as polyphenols and phenolic acids.

  3. Impact of structure and functionality of core polyol in highly functional biobased epoxy resins.

    Science.gov (United States)

    Pan, Xiao; Webster, Dean C

    2011-09-01

    Highly functional biobased epoxy resins were prepared using dipentaerythritol (DPE), tripentaerythritol (TPE), and sucrose as core polyols that were substituted with epoxidized soybean oil fatty acids, and the impact of structure and functionality of the core polyol on the properties of the macromolecular resins and their epoxy-anhydride thermosets was explored. The chemical structures, functional groups, molecular weights, and compositions of epoxies were characterized using nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI MS). The epoxies were also studied for their bulk viscosity, intrinsic viscosity, and density. Crosslinked with dodecenyl succinic anhydride (DDSA), epoxy-anhydride thermosets were evaluated using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile tests, and tests of coating properties. Epoxidized soybean oil (ESO) was used as a control. Overall, the sucrose-based thermosets exhibited the highest moduli, having the most rigid and ductile performance while maintaining the highest biobased content. DPE/TPE-based thermosets showed modestly better thermosetting performance than the control ESO thermoset.

  4. Rib Geometry Explains Variation in Dynamic Structural Response: Potential Implications for Frontal Impact Fracture Risk.

    Science.gov (United States)

    Murach, Michelle M; Kang, Yun-Seok; Goldman, Samuel D; Schafman, Michelle A; Schlecht, Stephen H; Moorhouse, Kevin; Bolte, John H; Agnew, Amanda M

    2017-05-25

    The human thorax is commonly injured in motor vehicle crashes, and despite advancements in occupant safety rib fractures are highly prevalent. The objective of this study was to quantify the ability of gross and cross-sectional geometry, separately and in combination, to explain variation of human rib structural properties. One hundred and twenty-two whole mid-level ribs from 76 fresh post-mortem human subjects were tested in a dynamic frontal impact scenario. Structural properties (peak force and stiffness) were successfully predicted (p geometry obtained via direct histological imaging (total area, cortical area, and section modulus) and were improved further when utilizing a combination of cross-sectional and gross geometry (robusticity, whole bone strength index). Additionally, preliminary application of a novel, adaptive thresholding technique, allowed for total area and robusticity to be measured on a subsample of standard clinical CT scans with varied success. These results can be used to understand variation in individual rib response to frontal loading as well as identify important geometric parameters, which could ultimately improve injury criteria as well as the biofidelity of anthropomorphic test devices (ATDs) and finite element (FE) models of the human thorax.

  5. Impact of coal structural heterogeneity on the nonideal sorption of organic contaminants.

    Science.gov (United States)

    Shi, Xin; Fu, Heyun; Li, Yuan; Mao, Jingdong; Zheng, Shourong; Zhu, Dongqiang

    2011-06-01

    Carbonaceous geosorbents (black carbon, coal, and humin/kerogen) play a primary role in the nonideal sorption (isotherm nonlinearity, hysteresis, and multiphasic kinetics) of hydrophobic organic chemicals by soils and sediments. The present study investigated the impact of coal structural heterogeneity on sorption/desorption of two model monoaromatic compounds (1,3-dichlorobenzene and 1,3-dinitrobenzene). Due to the higher degree of aromaticity and condensation, anthracite showed stronger sorption affinity and nonlinearity and slower sorption kinetics than lignite. Removal of humic substances by alkali extraction and/or mineral fraction by acidification did not much affect organic carbon-normalized sorption coefficient to the coal, suggesting nearly complete accessibility of adsorption sites on the condensed organic carbon. However, the treatments greatly increased sorption kinetics and meanwhile alleviated hysteresis of 1,3-dinitrobenzene, as compared with the original lignite. These observations were attributed to the enhanced exposure of high-energy adsorption sites on the condensed organic carbon after exfoliating the surface coverage by humic substances and minerals. An empirical biphasic pseudo-second-order model consisting of a fast sorption phase and a slow sorption phase adequately quantified the overall sorption kinetics for the coal sorbents. The results indicated that the condensed organic carbon, in combination with other structural components, controls the nonideal sorption of unburned coal. Copyright © 2011 SETAC.

  6. Modeling the Impact of Vegetation Structure on Canopy Radiative Transfer for a Global Vegetation Dynamic Model

    Science.gov (United States)

    Ni-Meister, W.; Kiang, N.; Yang, W.

    2007-12-01

    The transmission of light through plant canopies results in vertical profiles of light intensity that affect the photosynthetic activity and gas exchange of plants, their competition for light, and the canopy energy balance. The accurate representation of the canopy light profile is then important for predicting ecological dynamics. The study presents a simple canopy radiative transfer scheme to characterize the impact of the horizontal and vertical vegetation structure heterogeneity on light profiles. Actual vertical foliage profile and a clumping factor which are functions of tree geometry, size and density and foliage density are used to characterize the vertical and horizontal vegetation structure heterogeneity. The simple scheme is evaluated using the ground and airborne lidar data collected in deciduous and coniferous forests and was also compared with the more complex Geometric Optical and Radiative Transfer (GORT) model and the two-stream scheme currently being used to describe light interactions with vegetation canopy in most GCMs. The simple modeled PAR profiles match well with the ground data, lidar and full GORT model prediction, it performs much better than the simple Beer's&plaw used in two stream scheme. This scheme will have the same computation cost as the current scheme being used in GCMs, but provides better photosynthesis, radiative fluxes and surface albedo estimates, thus is suitable for a global vegetation dynamic model embedded in GCMs.

  7. Impact of stoichiometry on the electronic structure of PbS quantum dots.

    Science.gov (United States)

    Kim, Donghun; Kim, Dong-Ho; Lee, Joo-Hyoung; Grossman, Jeffrey C

    2013-05-10

    Although the stoichiometry of bulk lead sulfide (PbS) is exactly 1:1, that of quantum dots (QDs) can be considerably different from this crystalline limit. Employing first-principles calculations, we show that the impact of PbS QD stoichiometry on the electronic structure can be enormous, suggesting that control over the overall stoichiometry in the QD will play a critical role for improving the efficiency of optoelectronic devices made with PbS QDs. In particular, for bare PbS QDs, we find that: (i) stoichiometric PbS QDs are free from midgap states even without ligand passivation and independent of shape, (ii) off stoichiometry in PbS QDs introduces new states in the gap that are highly localized on certain surface atoms, and (iii) further deviations in stoichiometry lead to QDs with "metallic" behavior, with a dense number of energy states near the Fermi level. We further demonstrate that this framework holds for the case of passivated QDs by considering the attachment of ligand molecules as stoichiometry variations. Our calculations show that an optimal number of ligands makes the QD stoichiometric and heals unfavorable electronic structure, whereas too few or too many ligands cause effective off stoichiometry, resulting in QDs with defect states in the gap.

  8. Influence of Rare Earths on Improve Impact Property of Structural Alloy Steel with Extra Low Sulfur and Oxygen

    Institute of Scientific and Technical Information of China (English)

    Guo Feng; Lin Qin

    2007-01-01

    The influence of rare earth lanthanum and cerium on impact property of structural alloy steel with extra low sulfur and oxygen was studied by impact test and microanalysis. The results showed that rare earths increased impact power of the steel when their contents were about 0.005%. Proper addition of rare earths could purify grain boundaries and decrease amount of inclusions, and reduced the possibility of crack growth along grain boundaries and through inclusions. Therefore, such steel could absorb more crack growth energy while it was impacted. However, if the content of rare earths is excessive, the grain boundary would be weakened and brittle-hard phosphates and Fe-RE intermetallic would be formed, which worsened impact toughness of steel.

  9. Spatial structure and scale feature of the atmospheric pollution source impact of city agglomeration

    Institute of Scientific and Technical Information of China (English)

    XU; Xiangde; ZHOU; Xiuji; SHI; Xiaohui

    2005-01-01

    The spatial structure and multi-scale feature of the atmospheric pollution influence domain of Beijing and its peripheral areas (a rapidly developed city agglomeration) is dissected and analyzed in this paper on the basis of the atmospheric pollution dynamic-chemical process observation data of the urban building ensemble boundary layer of the Beijing City Air Pollution Observation Experiment (BECAPEX) in winter (February) and summer (August) 2003, and relevant meteorological elements and satellite retrieval aerosol optical depth (AOD), etc. comprehensive data with the dynamic-statistical integrated analysis of "point-surface" spatial structure. Results show that there existed significant difference in the contribution of winter/summer different pollution emission sources to the component character of atmospheric pollution, and the principal component analysis (PCA) results of statistical model also indicate that SO2 and NOX dominated in the component structure of winter aerosol particle; instead, CO and NOX dominated in summer. Surface layer atmospheric dynamic and thermal structures and various pollutant species at the upper boundary of building ensembles at urban different observational sites of Beijing in winter and summer showed an "in-phase" variation and its spatial scale feature of "influence domain". The power spectrum analysis (PSA) shows that the period spectrum of winter/summer particle concentration accorded with those of atmospheric wind field: the longer period was dominative in winter, but the shorter period in summer, revealing the impact of the seasonal scale feature of winter/summer atmospheric general circulation on the period of atmospheric pollution variations. It is found that from analyzing urban area thermal heterogeneity that the multiscale effect of Beijing region urban heat island (UHI) was associated with the heterogeneous expansion of tall buildings area. In urban atmospheric dynamical and thermal characteristic spatial structures, the

  10. Impacts of fullerene derivatives on regulating the structure and assembly of collagen molecules

    Science.gov (United States)

    Yin, Xiaohui; Zhao, Lina; Kang, Seung-Gu; Pan, Jun; Song, Yan; Zhang, Mingyi; Xing, Gengmei; Wang, Fei; Li, Jingyuan; Zhou, Ruhong; Zhao, Yuliang

    2013-07-01

    During cancer development, the fibrous layers surrounding the tumor surface get thin and stiff which facilitates the tumor metastasis. After the treatment of metallofullerene derivatives Gd@C82(OH)22, the fibrous layers become thicker and softer, the metastasis of tumor is then largely suppressed. The effect of Gd@C82(OH)22 was found to be related to their direct interaction with collagen and the resulting impact on the structure of collagen fibrils, the major component of extracellular matrices. In this work we study the interaction of Gd@C82(OH)22 with collagen by molecular dynamics simulations. We find that Gd@C82(OH)22 can enhance the rigidity of the native structure of collagen molecules and promote the formation of an oligomer or a microfibril. The interaction with Gd@C82(OH)22 may regulate further the assembly of collagen fibrils and change the biophysical properties of collagen. The control run with fullerene derivatives C60(OH)24 also indicates that C60(OH)24 can influence the structure and assembly of collagen molecules as well, but to a lesser degree. Both fullerene derivatives can form hydrogen bonds with multiple collagen molecules acting as a ``fullerenol-mediated bridge'' that enhance the interaction within or among collagen molecules. Compared to C60(OH)24, the interaction of Gd@C82(OH)22 with collagen is stronger, resulting in particular biomedical effects for regulating the biophysical properties of collagen fibrils.During cancer development, the fibrous layers surrounding the tumor surface get thin and stiff which facilitates the tumor metastasis. After the treatment of metallofullerene derivatives Gd@C82(OH)22, the fibrous layers become thicker and softer, the metastasis of tumor is then largely suppressed. The effect of Gd@C82(OH)22 was found to be related to their direct interaction with collagen and the resulting impact on the structure of collagen fibrils, the major component of extracellular matrices. In this work we study the interaction

  11. IMPACTS !

    CERN Multimedia

    2008-01-01

    (Photo courtesy of Don Davis / NASA)The University of Geneva (UNIGE) and the Ecole Polytechnique Fédérale of Lausanne (EPFL) are organising the 4th series of public lectures on astronomy, on the theme of "Impacts". The schedule is as follows: Il y a 100 ans : une explosion dans la Tunguska – Dr. Frédéric COURBIN, EPFL Les impacts sur Terre – Prof. Didier Queloz, UNIGE La fin des dinosaures – Dr. Stéphane Paltani, UNIGE Wednesday 7 May 2008, from 7.00 p.m. to 9.00 p.m. Auditoire CO1, EPFL, Ecublens Thursday 08 May 2008, from 7.00 p.m. to 9.00 p.m. Auditoire Rouiller, Uni-Dufour, Genève All 3 lectures will be givent each evening! Admission free Information: 022 379 22 00

  12. Research for improved health: variability and impact of structural characteristics in federally funded community engaged research.

    Science.gov (United States)

    Pearson, Cythina R; Duran, Bonnie; Oetzel, John; Margarati, Maya; Villegas, Malia; Lucero, Julie; Wallerstein, Nina

    2015-01-01

    Although there is strong scientific, policy, and community support for community-engaged research (CEnR)-including community-based participatory research (CBPR)-the science of CEnR is still developing. To describe structural differences in federally funded CEnR projects by type of research (i.e., descriptive, intervention, or dissemination/policy change) and race/ethnicity of the population served. We identified 333 federally funded projects in 2009 that potentially involved CEnR, 294 principal investigators/project directors (PI/PD) were eligible to participate in a key informant (KI) survey from late 2011 to early 2012 that asked about partnership structure (68% response rate). The National Institute on Minority Health & Health Disparities (19.1%), National Cancer Institute (NCI; 13.3%), and the Centers for Disease Control and Prevention (CDC; 12.6%) funded the most CEnR projects. Most were intervention projects (66.0%). Projects serving American Indian or Alaskan Native (AIAN) populations (compared with other community of color or multiple-race/unspecified) were likely to be descriptive projects (p<.01), receive less funding (p<.05), and have higher rates of written partnership agreements (p<.05), research integrity training (p<.05), approval of publications (p<.01), and data ownership (p<.01). AIAN-serving projects also reported similar rates of research productivity and greater levels of resource sharing compared with those serving multiple-race/unspecified groups. There is clear variability in the structure of CEnR projects with future research needed to determine the impact of this variability on partnering processes and outcomes. In addition, projects in AIAN communities receive lower levels of funding yet still have comparable research productivity to those projects in other racial/ethnic communities.

  13. A Study on External Fire Damage of Structures subjected to Aircraft Impact

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sang Shup [Hanyang University, Seoul (Korea, Republic of); Hahm, Daegi; Kim, Min Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    A large commercial aircraft consists of various components as fuselage, wings, fuel tank, engine etc. During a collision of the aircraft, the fuel tank with a large amount of jet fuel have a significant effect on the total load of the aircraft as well as causing explosive fire and smoke which affect the safety of the structure and equipment. US Sandia National Laboratories and Finland VTT etc. performed the test and simulation studies to evaluate the dispersion range of the fluid after the crash of liquid filled cylinder missiles. The test condition and results have been referred in this paper. The fluid modeling approach using SPH is applied to evaluate the dispersing range of the fluid, and is compared with the Brown's results. The jet fuel is idealized as particles contained in an aluminum cylinder missile, where those particles can be dispersed to the surrounding area after the missile crashes into a rigid target. The fluid model using the SPH method is briefly verified through comparison with test results, and then the modelling method is applied to a jet fuel model in an aircraft model. The dispersion analysis of jet fuel caused by aircraft impact is performed using an aircraft model for the determination of fire duration and fire affected zone in a nuclear power plant. Finally, the structural integrity of the roof of the structure during a jet fuel fire is evaluated. In this study, the filled jet fuel was modeled by using smooth particle hydrodynamics technique; jet fuel spread area following an aircraft crash was analyzed.

  14. Ocean acidification shows negligible impacts on high-latitude bacterial community structure in coastal pelagic mesocosms

    Directory of Open Access Journals (Sweden)

    A.-S. Roy

    2012-09-01

    Full Text Available The impact of ocean acidification and carbonation on microbial community structure was assessed during a large-scale in situ costal pelagic mesocosm study, included as part of the EPOCA 2010 Arctic campaign. The mesocosm experiment included ambient conditions (fjord and nine mesocosms, with pCO2 range from ~145 to ~1420 μatm. Samples collected at nine time points (t-1, t1, t5, t7, t12, t14, t22, t26 to t28 in seven treatments (ambient fjord (~145, 2×~185, ~270, ~685, ~820, ~1050 μatm were analysed for "free-living" and "particle associated" microbial community composition using 16S rRNA amplicon sequencing. This high-throughput sequencing analysis produced ~20 000 000 16S rRNA V4 reads, which comprised 7000 OTUs. The main variables structuring these communities were, sample origin (fjord or mesocosms and the filter size fraction (free-living or particle associated. The community was significantly different between the fjord and both the control and elevated 2 mesocosms (which were not significant different after nutrients were added to the mesocosms; suggesting that the addition of nutrients is the primary driver of the change in mesocosm community structure. The relative importance of each structuring variable depended greatly on the time at which the community was sampled in relation to the phytoplankton bloom. The size fraction was the second most important factor for community structure; separating free-living from particle-associated bacteria. When free-living and particle-associated bacteria were analysed separately at different time points, the only taxon pCO2 was found to significantly affect were the Gammaproteobacteria after nutrient addition. Finally, pCO2 treatment was found to be significantly correlated (non-linear with 15 rare taxa, most of which increased in abundance with higher CO2.

  15. Impact of oceanic submesoscale coherent structures on marine top predators: new tools and challenges

    Science.gov (United States)

    Tew-Kai, E.; Sudre, J.; Gremillet, D.; Yahia, H.; Rossi, V.; Hernandez-Garcia, E.; López, C.; Marsac, F.; Weimerskirch, H.; Garçon, V.

    2011-12-01

    In recent years it appears that meso- and submesoscale features (fronts, eddies, filaments) in surface ocean flow have a crucial influence on marine ecosystems. Their dynamics partly control the foraging behaviour and the movements of marine top. One of the challenges in ecology is to define critical habitats and understand the rules of habitat selection. Recently new tools for detection of coherent structures at submesoscale open the way for new studies never investigated before in marine ecology. Through two examples we highlight novel research on the importance of submesoscale structures for the spatial distribution of marine top predators. We studied two seabird populations with contrasting characteristics: Frigatebirds in the Mozambique Channel, and Cape gannets in the Benguela upwelling off southern Africa. Frigatebirds are mainly offshore birds while Cape gannets do not venture beyond the continental shelf. For these two studies, we used products derived from remote sensing data, to describe submesoscale coherent structures (Mozambique Channel resulting from an intense mesoscale activity. By comparing seabird satellite positions with LCSs locations, we demonstrate that frigatebirds track precisely these structures in the Mozambique Channel, providing the first evidence that a top predator is able to track these FSLE ridges to locate food patches. Although many questions remain unanswered, this work remains a pioneering on this topic. Despite the interest of FSLE, they are limited to offshore areas due to altimetry products limitation on continental shelves. However, many seabirds operate in coastal areas undergoing stronger anthropogenic pressures, such as Cape gannets off South Africa. The Benguela system is characterized by an upwelling inhabited by numerous fronts and filaments that very likely have a strong impact on seabird spatial distribution, and it was not possible to implement FSLE in this area. Thus, we used a newly developed method based on the

  16. Responsiveness of the major birch allergen Bet v 1 scaffold to the gastric environment: Impact on structure and allergenic activity

    DEFF Research Database (Denmark)

    Sancho, Ana I; Wangorsch, Andrea; Jensen, Bettina M

    2011-01-01

    Four Bet v 1 homologous food allergens from celeriac (rApi g 1), apple (rMal d 1), peach (rPru p 1) and hazelnut (rCor a 1), were used to probe the structural responsiveness of the Bet v 1 scaffold to gastric digestion conditions and its impact on allergenicity.......Four Bet v 1 homologous food allergens from celeriac (rApi g 1), apple (rMal d 1), peach (rPru p 1) and hazelnut (rCor a 1), were used to probe the structural responsiveness of the Bet v 1 scaffold to gastric digestion conditions and its impact on allergenicity....

  17. The transient fracture behavior for a functionally graded layered structure subjected to an in-plane impact load

    Institute of Scientific and Technical Information of China (English)

    Licheng Guo; Linzhi Wu; Yuguo Sun; Li Ma

    2005-01-01

    The transient fracture behavior of a functionally graded layered structure subjected to an in-plane impact load is investigated. The studied structure is composed of two homogeneous layers and a functionally graded interlayer with a crack perpendicular to the boundaries. The impact load is applied on the face of the crack. Fourier transform and Laplace transform methods are used to formulate the present problem in terms of a singular integral equation in Laplace transform domain. Considering variations of parameters such as the nonhomogeneity constant, the thickness ratio and the crack length, the dynamic stress intensity factors (DSIFs) in time domain are studied and some meaningful conclusions are obtained.

  18. Evidence for an impact-induced biosphere from the δ34S signature of sulphides in the Rochechouart impact structure, France

    Science.gov (United States)

    Simpson, S. L.; Boyce, A. J.; Lambert, P.; Lindgren, P.; Lee, M. R.

    2017-02-01

    The highly eroded 23 km diameter Rochechouart impact structure, France, has extensive evidence for post-impact hydrothermal alteration and sulphide mineralisation. The sulphides can be divided into four types on the basis of their mineralogy and host rock. They range from pyrites and chalcopyrite in the underlying coherent crystalline basement to pyrites hosted in the impactites. Sulphur isotopic results show that δ34S values vary over a wide range, from -35.8‰ to +0.4‰. The highest values, δ34S -3.7‰ to +0.4‰, are recorded in the coherent basement, and likely represent a primary terrestrial sulphur reservoir. Sulphides with the lowest values, δ34S -35.8‰ to -5.2‰, are hosted within locally brecciated and displaced parautochthonous and autochthonous impactites. Intermediate δ34S values of -10.7‰ to -1.2‰ are recorded in the semi-continuous monomict lithic breccia unit, differing between carbonate-hosted sulphides and intraclastic and clastic matrix-hosted sulphides. Such variable isotope values are consistent with a biological origin, via bacterial sulphate reduction, for sulphides in the parautochthonous and autochthonous units; these minerals formed in the shallow subsurface and are probably related to the post impact hydrothermal system. The source of the sulphate is likely to have been seawater, penecontemporaneous to the impact, as inferred from the marginal marine paleogeography of the structure. In other eroded impact craters that show evidence for impact-induced hydrothermal circulation, indirect evidence for life may be sought isotopically within late-stage (≤120 °C) secondary sulphides and within the shocked and brecciated basement immediately beneath the transient crater floor.

  19. Microscopic Effects of Shock Metamorphism in Crystalline Rocks Correlated With Shock Induced Changes in Density, Haughton Impact Structure

    Science.gov (United States)

    Singleton, A. C.; Osinski, G.; Moser, D.

    2009-05-01

    Asteroid and comet impacts are an important geological process on all solid planetary bodies, including Earth, and involve pressures and temperatures that may reach several hundred GPa and several thousand K [1] over very limited spatial and temporal scales. This results in shock metamorphism and alters the target material on both megascopic and microscopic scales [2]. Many shock metamorphic features are unique to hypervelocity impact environments and are, therefore, diagnostic of such an event [1,2]. Of particular interest for this study is the effect of hypervelocity impact on the density of the target material. In the case of crystalline target rocks, shock metamorphism results in an increase of pore space and impact induced fractures which act to decrease the density. The Haughton impact structure is a well-preserved late Eocene (39 ± 2 Ma) complex impact structure, situated near the western end of Devon Island (75°22'N, 89°41'W) [3]. The geology of the area consists of a sedimentary sequence unconformably overlying crystalline Precambrian gneisses of the Canadian Shield. Since the impact, Devon Island has remained tectonically stable and Haughton remains well-preserved despite being subjected to several glaciations. The excellent preservation of the structure is largely due to the primarily cold and relatively dry environment that has existed in the Arctic since the Eocene [3]. Samples of crystalline material were collected from 36 sites within the impact breccia unit of the Haughton impact structure. These samples display a wide range of density and physical appearance. The type of shock effect(s) created depends upon the pressures and temperatures involved as well as the composition, density and material's location in the target. The samples found in the Haughton impact structure show a wide range of shock effects and thus were exposed to a variety of different conditions likely due to their in-situ positions relative to the impact. Polished thin sections

  20. Ion Acceleration at Earth, Saturn and Jupiter and its Global Impact on Magnetospheric Structure

    Science.gov (United States)

    Brandt, Pontus

    2016-07-01

    The ion plasma pressures at Earth, Saturn and Jupiter are significant players in the electrodynamic force-balance that governs the structure and dynamics of these magnetospheres. There are many similarities between the physical mechanisms that are thought to heat the ion plasma to temperatures that even exceed those of the solar corona. In this presentation we compare the ion acceleration mechanisms at the three planetary magnetospheres and discuss their global impacts on magnetopsheric structure. At Earth, bursty-bulk flows, or "bubbles", have been shown to accelerate protons and O+ to high energies by the earthward moving magnetic dipolarization fronts. O+ ions display a more non-adiabatic energization in response to these fronts than protons do as they are energized and transported in to the ring-current region where they reach energies of several 100's keV. We present both in-situ measurements from the NASA Van Allen Probes Mission and global Energetic Neutral (ENA) images from the High-Energy Neutral Atom (HENA) Camera on board the IMAGE Mission, that illustrate these processes. The global impact on the magnetospheric structure is explored by comparing the empirical magnetic field model TS07d for given driving conditions with global plasma pressure distributions derived from the HENA images. At Saturn, quasi-periodic energization events, or large-scale injections, occur beyond about 9 RS around the post-midnight sector, clearly shown by the Ion and Neutral Atom Camera (INCA) on board the Cassini mission. In contrast to Earth, the corotational drift dominates even the energetic ion distributions. The large-scale injections display similar dipolarization front features can be found and there are indications that like at Earth the O+ responds more non-adiabatically than protons do. However, at Saturn there are also differences in that there appears to be energization events deep in the inner magnetosphere (6-9 RS) preferentially occurring in the pre

  1. Impacts of temperature on primary productivity and respiration in naturally structured macroalgal assemblages.

    Directory of Open Access Journals (Sweden)

    Leigh W Tait

    Full Text Available Rising global temperatures caused by human-mediated change has already triggered significant responses in organismal physiology, distribution and ecosystem functioning. Although the effects of rising temperature on the physiology of individual organisms are well understood, the effect on community-wide processes has remained elusive. The fixation of carbon via primary productivity is an essential ecosystem function and any shifts in the balance of primary productivity and respiration could alter the carbon balance of ecosystems. Here we show through a series of tests that respiration of naturally structured algal assemblages in southern New Zealand greatly increases with rising temperature, with implications for net primary productivity (NPP. The NPP of in situ macroalgal assemblages was minimally affected by natural temperature variation, possibly through photo-acclimation or temperature acclimation responses, but respiration rates and compensating irradiance were negatively affected. However, laboratory experiments testing the impacts of rising temperature on several photosynthetic parameters showed a decline in NPP, increasing respiration rates and increasing compensating irradiance. The respiration Q10 of laboratory assemblages (the difference in metabolic rates over 10°C averaged 2.9 compared to a Q10 of 2 often seen in other autotrophs. However, gross primary productivity (GPP Q10 averaged 2, indicating that respiration was more severely affected by rising temperature. Furthermore, combined high irradiance and high temperature caused photoinhibition in the laboratory, and resulted in 50% lower NPP at high irradiance. Our study shows that communities may be more severely affected by rising global temperatures than would be expected by responses of individual species. In particular, enhanced respiration rates and rising compensation points have the potential to greatly affect the carbon balance of macroalgal assemblages through declines in

  2. Heterotrophic microbial colonization of the interior of impact-shocked rocks from Haughton impact structure, Devon Island, Nunavut, Canadian High Arctic

    Science.gov (United States)

    Fike, David A.; Cockell, Charles; Pearce, David; Lee, Pascal

    2002-10-01

    The polar desert is one of the most extreme environments on Earth. Endolithic organisms can escape or mitigate the hazards of the polar desert by using the resources available in the interior of rocks. We examined endolithic communities within crystalline rocks that have undergone shock metamorphism as a result of an asteroid or comet impact. Specifically, we present a characterization of the heterotrophic endolithic community and its environment in the interior of impact-shocked gneisses and their host polymict breccia from the Haughton impact structure on Devon Island, Nunavut, Canadian High Arctic. Microbiological colonization of impact-shocked rocks is facilitated by impact-induced fissures and cavities, which occur throughout the samples, the walls of which are lined with high abundances of biologically important elements owing to the partial volatilization of minerals within the rock during the impact. 27 heterotrophic bacteria were isolated from these shocked rocks and were identified by 16S rDNA sequencing. The isolates from the shocked gneiss and the host breccia are similar to each other, and to other heterotrophic communities isolated from polar environments, suggesting that the interiors of the rocks are colonized by microorganisms from the surrounding country rocks and soils. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were used to identify the chemical composition of the shocked materials and to document the in situ growth of microbes in their interiors. The identification of these heterotrophic communities within impact-shocked crystalline rocks extends our knowledge of the habitable biosphere on Earth. The colonization of the interiors of these samples has astrobiological applications both for considering terrestrial, microbiological contamination of meteorites from the Antarctic ice sheet and for investigating possible habitats for microbial

  3. A meta-analysis on the impacts of partial cutting on forest structure and carbon storage

    Science.gov (United States)

    Zhou, D.; Zhao, S. Q.; Liu, S.; Oeding, J.

    2013-06-01

    Partial cutting, which removes some individual trees from a forest, is one of the major and widespread forest management practices that can significantly alter both forest structure and carbon (C) storage. Using 748 observations from 81 studies published between 1973 and 2011, we synthesized the impacts of partial cutting on three variables associated with forest structure (mean annual growth of diameter at breast height (DBH), stand basal area, and volume) and four variables related to various C stock components (aboveground biomass C (AGBC), understory C, forest floor C, and mineral soil C). Results show that the growth of DBH increased by 111.9% after partial cutting, compared to the uncut control, with a 95% bootstrapped confidence interval ranging from 92.2 to 135.9%, while stand basal area and volume decreased immediately by 34.2% ([-37.4%, -31.2%]) and 28.4% ([-32.0%, -25.1%]), respectively. On average, partial cutting reduced AGBC by 43.4% ([-47.7%, -39.3%]), increased understory C storage by 391.5% ([220.0%, 603.8%]), but did not show significant effects on C stocks on forest floor and in mineral soil. All the effects, if significant (i.e., on DBH growth, stand basal area, volume, and AGBC), intensified linearly with cutting intensity and decreased linearly over time. Overall, cutting intensity had more strong impacts than the length of recovery time on the responses of those variables to partial cutting. Besides the significant influence of cutting intensity and recovery time, other factors such as climate zone and forest type also affected forest responses to partial cutting. For example, a large fraction of the changes in DBH growth remains unexplained, suggesting the factors not included in the analysis may play a major role. The data assembled in this synthesis were not sufficient to determine how long it would take for a complete recovery after cutting because long-term experiments were scarce. Future efforts should be tailored to increase the

  4. Combined assessment of the environmental, economic and social impacts of structural solutions for residential construction

    Directory of Open Access Journals (Sweden)

    Fraile-García, E.

    2015-09-01

    Full Text Available Sustainable development in construction is based on three fundamental pillars: economic, environmental and social. This type of approach aims to identify the best possible solutions for sustainably developing structures by conducting a joint evaluation of the impact on those three pillars. The proposed methodology incorporates metadata on the Spanish construction sector. First, a discrete database is generated with 360 alternatives covering a range of common solutions in residential building. A Pareto algorithm is utilized to select the optimal choices and the wide range of solutions is reduced to the 5 % of the initial group. The project manager is therefore provided with an objective assessment of suitable structural alternatives including the overall joint economic, social, and environmental impact. The results obtained demonstrate the importance and utility of the proposed methodology for sustainable construction.El desarrollo sostenible aplicado a la construcción se basa en tres pilares fundamentales: económico, medioambiental y social. El objetivo principal es identificar las mejores soluciones en términos de desarrollo sostenible de alternativas estructurales a partir de la evaluación conjunta de los impactos en dichos pilares. La metodología propuesta incorpora metadatos con información del sector de la construcción en España. Primero se genera una base de datos discreta de 360 alternativas estructurales que cubren el rango de soluciones habituales en edificación residencial. La selección de alternativas óptimas se realiza mediante el algoritmo de Pareto. El abanico de soluciones se reduce al 5 % de las iniciales. Se aporta una valoración objetiva que orienta al proyectista en la selección de alternativas estructurales idóneas, visualizando de forma conjunta el impacto económico, social y ambiental. Los resultados obtenidos muestran la importancia y utilidad de la metodología propuesta en el campo de la construcci

  5. Impact of the Family Structure on Satisfaction with Household Income in Urban Peru

    Directory of Open Access Journals (Sweden)

    Gustavo Riesco Lind

    2016-02-01

    Full Text Available Family structure affects not only household income but can influence how revenues contributeto financial satisfaction. That is to say, it is possible that a certain family structure can be more efficient in producing satisfaction than another. Using microdata from the National Household Survey (ENAHO 2013, a probit econometric model is proposed for urban households in Peru, in which the likelihood of satisfaction with household income is a function of income itself, both in absolute terms and relative to other households, and of various household characteristics, including aspects of family structure. Analysis of ENAHO 2013 reveals that 80.2% of house- holds report being satisfied with their income; satisfaction levels among lone parents are the lower than in other groups (77.3% and the highest satisfaction levels are reported by married couples with children and cohabiting couples with children (82.8% and 80.3% respectively. Results of the regression model support the conclusions of other studies, in that per capita hou- sehold income has a positive impact on the probability of income satisfaction; however, it is not the only significant variable. In particular, we have found evidence that the difference between household expenditure and average household expenditure in the region (a measure of relative expenditure also influences the likelihood of income satisfaction, as well as changes in household economy relative to that of other households in the area. Regarding family structures considered in the study, households of married couples with children, cohabiting couples with children, and cohabiting couples without children are less responsive than other households in several variables: number of household members, income per capita, difference between household expenditure and the regional average, and university education of the household head. In single- parent households in general, satisfaction with income is

  6. Spatial structure and scale feature of the atmospheric pollution source impact of city agglomeration

    Institute of Scientific and Technical Information of China (English)

    XU Xiangde; ZHOU Xiuji; SHI Xiaohui

    2005-01-01

    The spatial structure and multi-scale feature of the atmospheric pollution influence domain of Beijing and its peripheral areas (a rapidly developed city agglomeration) is dissected and analyzed in this paper on the basis of the atmospheric pollution dynamic-chemical process observation data of the urban building ensemble boundary layer of the Beijing City Air Pollution Observation Experiment (BECAPEX) in winter (February) and summer (August) 2003, and relevant meteorological elements and satellite retrieval aerosol optical depth (AOD), etc. comprehensive data with the dynamic-statistical integrated analysis of "point-surface" spatial structure. Results show that there existed significant difference in the contribution of winter/summer different pollution emission sources to the component character of atmospheric pollution, and the principal component analysis (PCA) results of statistical model also indicate that SO2 and NOX dominated in the component structure of winter aerosol particle; instead, CO and NOX dominated in summer. Surface layer atmospheric dynamic and thermal structures and various pollutant species at the upper boundary of building ensembles at urban different observational sites of Beijing in winter and summer showed an "in-phase" variation and its spatial scale feature of "influence domain". The power spectrum analysis (PSA) shows that the period spectrum of winter/summer particle concentration accorded with those of atmospheric wind field: the longer period was dominative in winter, but the shorter period in summer, revealing the impact of the seasonal scale feature of winter/summer atmospheric general circulation on the period of atmospheric pollution variations. It is found that from analyzing urban area thermal heterogeneity that the multiscale effect of Beijing region urban heat island (UHI) was associated with the heterogeneous expansion of tall buildings area. In urban atmospheric dynamical and thermal characteristic spatial structures, the

  7. Paleomagnetic Investigations of the Decaturville, MO, and Sierra Madera, TX, Impact Structures

    Science.gov (United States)

    Dulin, S. A.; Elmore, R. D.; Dennie, D. P.; Evans, S. C.; Mulvany, P.

    2011-03-01

    In this study we are testing if a modified paleomagnetic conglomerate test on impact breccias, in conjunction with geochemical/petrographic studies, can be used to constrain the timing of the impacts and determine the origin of carbonate breccias.

  8. The dominating impact of small-scale streambed structural heterogeneity on hyporheic exchange and biogeochemical hotspots in lowland rivers

    Science.gov (United States)

    Krause, S.; Gomez, J. D.; Blume, T.; Weatherill, J.; Angermann, L.; Munz, M.; Tecklenburg, C.; Cassidy, N. J.; Wilson, J. L.

    2013-12-01

    Exchange fluxes and residence times of groundwater and surface water at aquifer-river interfaces are driven by hydrodynamic and hydrostatic forcing. While previous research, with a predominantly surface water perspective, has mainly focussed on the impact of bedform controlled advective pumping on hyporheic zone extent and residence times, little attention has been paid to the impact of streambed structural controls on groundwater up-welling patterns and its implications for hyporheic exchange. Following a combined experimental and model-based approach, this paper highlights the impact of small-scale streambed structural variability on spatial patterns of hyporheic exchange flow, residence time distribution and the development of hotspots of biogeochemical cycling in the hyporheic zone of a lowland river. Combining Fibre-optic DTS and active Heat Pulse Sensing, this study identified distinct low conductivities peat and clay structures in the streambed to determine patterns, quantity and temporal dynamics of groundwater up-welling. Model simulations confirmed that streambed structure controlled patterns of groundwater up-welling exceeded the impact of bedform driven fluxes on aquifer-river exchange flow patterns. In addition, enhanced residence times of up-welling groundwater in and around these organic rich structures lead to an increase in dissolved oxygen consumption and the development of anaerobic denitrification hotspots. The resulting increases in streambed nitrate attenuation as well as enhanced production of CO2, CH4 and N2O as respiration end products highlight the importance of biogeochemical hotspots at aquifer-river interfaces under the dominant impact of streambed structural heterogeneity. Conceptual model of streambed hydrofacies controlling groundwater up-welling in a typical lowland river including their effect on heat transport at the aquifer-river interface (the star indicates the temperature of the surface water). B: core logs of exemplary

  9. A Reassessment of the Impact of European Contact on the Structure of Native American Genetic Diversity.

    Science.gov (United States)

    Hunley, Keith; Gwin, Kiela; Liberman, Brendan

    2016-01-01

    Our current understanding of pre-Columbian history in the Americas rests in part on several trends identified in recent genetic studies. The goal of this study is to reexamine these trends in light of the impact of post-Columbian admixture and the methods used to study admixture. The previously-published data consist of 645 autosomal microsatellite genotypes from 1046 individuals in 63 populations. We used STRUCTURE to estimate ancestry proportions and tested the sensitivity of these estimates to the choice of the number of clusters, K. We used partial correlation analyses to examine the relationship between gene diversity and geographic distance from Beringia, controlling for non-Native American ancestry (from Africa, Europe and East Asia), and taking into account alternative paths of migration. Principal component analysis and multidimensional scaling were used to investigate the relationships between Andean and non-Andean populations and to explore gene-language correspondence. We found that 1) European and East Asian ancestry estimates decline as K increases, especially in Native Canadian populations, 2) a north-south decline in gene diversity is driven by low diversity in Amazonian and Paraguayan populations, not serial founder effects from Beringia, 3) controlling for non-Native American ancestry, populations in the Andes and Mesoamerica have higher gene diversity than populations in other regions, and 4) patterns of genetic and linguistic diversity are poorly correlated. We conclude that patterns of diversity previously attributed to pre-Columbian processes may in part reflect post-Columbian admixture and the choice of K in STRUCTURE analyses. Accounting for admixture, the pattern of diversity is inconsistent with a north-south founder effect process, though the genetic similarities between Mesoamerican and Andean populations are consistent with rapid dispersal along the western coast of the Americas. Further, even setting aside the disruptive effects of

  10. Impact of physiology, structure and BRDF in hyperspectral time series of a Citrus orchard

    Science.gov (United States)

    Stuckens, J.; Dzikiti, S.; Verstraeten, W. W.; Verreynne, J. S.; Swinnen, R.; Coppin, P.

    2010-05-01

    Monitoring of plant production systems using remote sensing requires an understanding of the mechanisms in which physiological and structural changes as well as the quality and direction of incident light alter the measured canopy reflectance. Due to the evergreen nature of Citrus, the benefits of year-round monitoring of spectral changes are counterweighted by more subtle changes and seasonal trends than in other perennials. This study presents the results of a 14 months field measurement campaign in a commercial Citrus sinensis ‘Midknight Valencia' orchard in Wellington, Western Cape Province, South-Africa. Hyperspectral data were collected of canopy and leaf reflectance (350 - 2500 nm) of 16 representative trees at monthly intervals and supplemented with local climatology, orchard management records, sap stream, water potential and leaf and soil nutrient analysis. The aim of this research is to translate spectral changes and trends at the leaf and at canopy levels into physiological processes such as plant nutrient and carbohydrate balances and stress responses. Specific research questions include the spectral detection of flowering (date of anthesis, flowering intensity), fruit drop, fruit number and coloration, vegetative flushes, leaf senescence and drop and pruning. Attention is paid to the detection and the impact of sunburn (photo-damage). In order to separate physiological and structural changes from changes caused by seasonal changes in solar elevation during measurement time (bidirectional reflectance) a normalization function is constructed using simulated and measured data. Additional research is done to up-scale measurements from tree level to orchard level, which includes the tree variability, the influence of soil and weeds and different amounts of shading.

  11. Impact of food model (micro)structure on the microbial inactivation efficacy of cold atmospheric plasma.

    Science.gov (United States)

    Smet, C; Noriega, E; Rosier, F; Walsh, J L; Valdramidis, V P; Van Impe, J F

    2017-01-02

    The large potential of cold atmospheric plasma (CAP) for food decontamination has recently been recognized. Room-temperature gas plasmas can decontaminate foods without causing undesired changes. This innovative technology is a promising alternative for treating fresh produce. However, more fundamental studies are needed before its application in the food industry. The impact of the food structure on CAP decontamination efficacy of Salmonella Typhimurium and Listeria monocytogenes was studied. Cells were grown planktonically or as surface colonies in/on model systems. Both microorganisms were grown in lab culture media in petri dishes at 20°C until cells reached the stationary phase. Before CAP treatment, cells were deposited in a liquid carrier, on a solid(like) surface or on a filter. A dielectric barrier discharge reactor generated helium-oxygen plasma, which was used to treat samples up to 10min. Although L. monocytogenes is more resistant to CAP treatment, similar trends in inactivation behavior as for S. Typhimurium are observed, with log reductions in the range [1.0-2.9] for S. Typhimurium and [0.2-2.2] for L. monocytogenes. For both microorganisms, cells grown planktonically are easily inactivated, as compared to surface colonies. More stressing growth conditions, due to cell immobilization, result in more resistant cells during CAP treatment. The main difference between the inactivation support systems is the absence or presence of a shoulder phase. For experiments in the liquid carrier, which exhibit a long shoulder, the plasma components need to diffuse and penetrate through the medium. This explains the higher efficacies of CAP treatment on cells deposited on a solid(like) surface or on a filter. This research demonstrates that the food structure influences the cell inactivation behavior and efficacy of CAP, and indicates that food intrinsic factors need to be accounted when designing plasma treatment.

  12. Game Immersion Experience: Its Hierarchical Structure and Impact on Game-Based Science Learning

    Science.gov (United States)

    Cheng, M.-T.; She, H.-C.; Annetta, L. A.

    2015-01-01

    Many studies have shown the positive impact of serious educational games (SEGs) on learning outcomes. However, there still exists insufficient research that delves into the impact of immersive experience in the process of gaming on SEG-based science learning. The dual purpose of this study was to further explore this impact. One purpose was to…

  13. Mathematical simulation of the behavior of materials and structural elements under multiple impact loading

    Science.gov (United States)

    Belov, N. N.; Yugov, N. T.; Kopanitsa, D. G.; Tabachenko, A. N.; Afanas'eva, S. A.; Yugov, A. A.; Arkhipov, I. N.

    2010-06-01

    A method of computer simulation is used to investigate the processes of compact cylindrical projectile penetration into steel specimens separated by air gaps during successive group impacts, impact interaction of long steel bars with an explosive screened by a system of spatially separated multilayered screens, and fracture of ferroconcrete columns under repeated longitudinal and transverse impact loading.

  14. Extraterrestrial Helium (He@C60) Trapped in Fullerenes in the Sudbury Impact Structure

    Science.gov (United States)

    Becker, L.; Bada, J. L.; Poreda, R. J.; Bunch, T. E.

    1997-01-01

    Fullerenes (C60 and C70) have recently been identified in a shock-produced breccia (Onaping Formation) associated with the 1.85-Ga Sudbury Impact Crater. The presence of parts-per-million levels of fullerenes in this impact structure raises interesting questions about the processes that led to the formation of fullerenes and the potential for delivery of intact organic material to the Earth by a large bolide (e.g., asteroid or comet). Two possible scenarios for the presence of fullerenes in the Sudbury impact deposits are that (1) fullerenes are synthesized within the impact plume from the C contained in the bolide; or (2) fullerenes are already present in the bolide and survived the impact event. The correlation of C and trapped noble gas atoms in meteorites is well established. Primitive meteorites contain several trapped noble gas components that have anomalous isotopic compositions, some of which may have a presolar origin. Several C-bearing phases, including SiC, graphite, and diamond, have been recognized as carriers of trapped noble gases. It has also been suggested that fullerenes (C60 and C70) might be a carrier of noble gas components in carbonaceous chondrites. Recently, fullerenes have been detected in separate samples in the Allende meteorite. Carbon-60 is large enough to enclose the noble gases He, Ne, Ar, Kr, and Xe, but it is too small to contain diatomic gases such as N2 or triatomic gases such as CO2. Recent experimental work has demonstrated that noble gases of a specific isotopic composition can be introduced into synthetic fullerenes at high temperatures and pressures; these encapsulated gases can then be released by the breaking of one or more C bonds during step-heating under vacuum. These thermal-release patterns for He encapsulated within the C60 molecule (He@C60) are similar to the patterns for acid residues of carbonaceous chondrites, suggesting that fullerenes could be an additional carrier of trapped noble gases in acid residues of

  15. Extraterrestrial Helium (He@C60) Trapped in Fullerenes in the Sudbury Impact Structure

    Science.gov (United States)

    Becker, L.; Bada, J. L.; Poreda, R. J.; Bunch, T. E.

    1997-01-01

    Fullerenes (C60 and C70) have recently been identified in a shock-produced breccia (Onaping Formation) associated with the 1.85-Ga Sudbury Impact Crater. The presence of parts-per-million levels of fullerenes in this impact structure raises interesting questions about the processes that led to the formation of fullerenes and the potential for delivery of intact organic material to the Earth by a large bolide (e.g., asteroid or comet). Two possible scenarios for the presence of fullerenes in the Sudbury impact deposits are that (1) fullerenes are synthesized within the impact plume from the C contained in the bolide; or (2) fullerenes are already present in the bolide and survived the impact event. The correlation of C and trapped noble gas atoms in meteorites is well established. Primitive meteorites contain several trapped noble gas components that have anomalous isotopic compositions, some of which may have a presolar origin. Several C-bearing phases, including SiC, graphite, and diamond, have been recognized as carriers of trapped noble gases. It has also been suggested that fullerenes (C60 and C70) might be a carrier of noble gas components in carbonaceous chondrites. Recently, fullerenes have been detected in separate samples in the Allende meteorite. Carbon-60 is large enough to enclose the noble gases He, Ne, Ar, Kr, and Xe, but it is too small to contain diatomic gases such as N2 or triatomic gases such as CO2. Recent experimental work has demonstrated that noble gases of a specific isotopic composition can be introduced into synthetic fullerenes at high temperatures and pressures; these encapsulated gases can then be released by the breaking of one or more C bonds during step-heating under vacuum. These thermal-release patterns for He encapsulated within the C60 molecule (He@C60) are similar to the patterns for acid residues of carbonaceous chondrites, suggesting that fullerenes could be an additional carrier of trapped noble gases in acid residues of

  16. Modeling of Local BEAM Structure for Evaluation of MMOD Impacts to Support Development of a Health Monitoring System

    Science.gov (United States)

    Lyle, Karen H.; Vassilakos, Gregory J.

    2015-01-01

    This report summarizes initial modeling of the local response of the Bigelow Expandable Activity Module (BEAM) to micrometeorite and orbital debris (MMOD) impacts using a structural, non-linear, transient dynamic finite element code. Complementary test results for a local BEAM structure are presented for both hammer and projectile impacts. Review of these data provided guidance for the transient dynamic model development. The local model is intended to support predictions using the global BEAM model, described in a companion report. Two types of local models were developed. One mimics the simplified Soft-Goods (fabric envelop) part of the BEAM NASTRAN model delivered by the project. The second investigates through-the-thickness modeling challenges for MMOD-type impacts. Both the testing and the analysis summaries contain lessons learned and areas for future efforts.

  17. The Impact of Complexity, Rate of Change and Information Availability on the Production Planning and Control Structure

    NARCIS (Netherlands)

    M.F. van Assen (Marcel); S.L. van de Velde (Steef)

    2003-01-01

    textabstractThe organizational theory literature argues that the more uncertain the environment, the more likely the firm’s operational decision structure is decentralized. However, it remains unclear which uncertainty dimensions (i.e. complexity, rate of change and lack of information) impacts the

  18. Human impacts on forest structure and species richness on the edges of a. protected mountain forest in Uganda

    NARCIS (Netherlands)

    Sassen, M.; Sheil, D.

    2013-01-01

    We investigated how local scale variation in human impacts influenced forest structure and tree species richness within Mt Elgon National Park, Uganda. We assessed basal area (BA), stem density, diameter at breast height (dbh) and indicators of human activity in 343 plots in four study sites, on tra

  19. Impact of double-logarithmic electroweak radiative corrections on the non-singlet structure functions at small x

    CERN Document Server

    Ermolaev, B I

    2008-01-01

    In the QCD context, the non-singlet structure functions of u and d -quarks are identical, save the initial quark densities. Electroweak radiative corrections, being flavor-dependent, bring further difference between the non-singlets. This difference is calculated in the double-logarithmic approximation and the impact of the electroweak corrections on the non-singlet intercepts is estimated numerically.

  20. The Impact of Complexity, Rate of Change and Information Availability on the Production Planning and Control Structure

    NARCIS (Netherlands)

    M.F. van Assen (Marcel); S.L. van de Velde (Steef)

    2003-01-01

    textabstractThe organizational theory literature argues that the more uncertain the environment, the more likely the firm’s operational decision structure is decentralized. However, it remains unclear which uncertainty dimensions (i.e. complexity, rate of change and lack of information) impacts the

  1. Perceptions of postgraduate trainees on the impact of objective structured clinical examinations on their study behavior and clinical practice

    NARCIS (Netherlands)

    Opoka, Robert O; Kiguli, Sarah; Ssemata, Andrew S; Govaerts, Marjan; Driessen, Erik W

    2015-01-01

    BACKGROUND: The objective structured clinical examination (OSCE) is a commonly used method of assessing clinical competence at various levels, including at the postgraduate level. How the OSCE impacts on learning in higher education is poorly described. In this study, we evaluated the perceptions of

  2. Impact of African elephants on baobab (Adansonia digitata L.) population structure in northern Gonarezhou National Park, Zimbabwe

    NARCIS (Netherlands)

    Kupika, O.L.; Kativu, S.; Gandiwa, E.; Gumbie, A.

    2014-01-01

    The impact of African elephant (Loxodonta africana) on population structure of baobab trees (Adansonia digitata L.) was assessed in northern Gonarezhou National Park (GNP), southeast Zimbabwe. Baobabs were sampled in March 2008 and September 2012 using 11 randomly laid belt transects of variable len

  3. About the Same Geological Age and Possible Simultaneous Formation of Obolon' (Ukraine) and Puchezch-Katun' (Russia) Impact Structures

    Science.gov (United States)

    Valter, A. A.; Maschak, M. S.

    2012-03-01

    Structures have Bajocian ages of primary crater sediments and the K-Ar ages of impact glasses: 168 ± 5 Ma (Obolon’) and 167 ± 3 Ma (Puchezch- Katun’). Direction of O elongation coincides with (O)-(P) line. They might be formed by the same projectile.

  4. Autonomous versus Merged Marketing Departments: The Impact of Current Department Structure and Previous Restructuring Experience on Faculty Perceptions

    Science.gov (United States)

    Neese, William T.; Batory, Stephen S.

    2005-01-01

    This study details faculty perceptions concerning administrative structure and its impact on issues such as collegiality or student success. Faculty members in autonomous marketing departments are compared with those in combined units. Then, faculty never involved with departmental change are compared with faculty previously involved splitting…

  5. Discovery of Possible Meteoritic Matter on Shatter Cones — 2. Clearwater East Impact Structure, Québec, Canada

    Science.gov (United States)

    Buchner, E.; Schmieder, M.

    2016-08-01

    In the frame of the “Shatter Cone Coatings Project,” we investigated shatter cones from the Clearwater East impact structure that contain several Fe-Ni-Co metal and metal oxide particles (kamacite and taenite) and a sulfide particle (troilite?).

  6. Structural soil crust development from raindrop impacts using two-dimensional discrete element method

    Science.gov (United States)

    Yeom, Seungcheol; Sjoblom, Kurt

    2016-12-01

    The mechanical nature of crust formation as a result of raindrop impacts was simulated within a discrete element modeling environment. Simulations were conducted in two-dimensions (2D) using both linear and non-linear elastic contact models. The 2D approach was found to minimize the computational effort required and maximize the number of particles in the soil profile. For the non-linear model, the effect of the coefficient of restitution (COR) for soil-rain and soil-soil was investigated. Finally, the comparison between the linear and nonlinear elastic contact model was presented. The simulation indicated that the COR for rain-soil had negligible effect on the crust development but the computational time was exponentially increased with increasing coefficient value. In contrast, the COR for soil-soil had a dominant influence on the crust development. To validate the numerical results, a micro computerized tomography (microCT) technique was applied to characterize the changes in pore structure to a USCS SP soil after exposure under a rainfall simulator. Additionally, the effect of cyclic wetting and drying (without rainfall) on the changes in porosity was investigated. The experimental results showed that the rainfall simulator sufficiently densified the soil but the effect of cyclic wetting and drying was negligible. The numerical simulations showed similar changes in porosity along the depth of the soil profile as compared with the experimental results thus validating the DEM technique to simulate crust development.

  7. Design, synthesis, and biological activities of closantel analogues: structural promiscuity and its impact on Onchocerca volvulus.

    Science.gov (United States)

    Garner, Amanda L; Gloeckner, Christian; Tricoche, Nancy; Zakhari, Joseph S; Samje, Moses; Cho-Ngwa, Fidelis; Lustigman, Sara; Janda, Kim D

    2011-06-09

    Onchocerciasis, or river blindness, is a neglected tropical disease that affects more than 37 million people worldwide, primarily in Africa and Central and South America. We have disclosed evidence that the larval-stage-specific chitinase, OvCHT1, may be a potential biological target for affecting nematode development. On the basis of screening efforts, closantel, a known anthelmintic drug, was discovered as a potent and highly specific OvCHT1 inhibitor. Originally, closantel's anthelmintic mode of action was believed to rely solely on its role as a proton ionophore; thus, the impact of each of its biological activities on O. volvulus L3 molting was investigated. Structure-activity relationship studies on an active closantel fragment are detailed, and remarkably, by use of a simple salicylanilide scaffold, compounds acting only as protonophores or chitinase inhibitors were identified. From these data, unexpected synergistic protonophore and chitinase inhibition activities have also been found to be critical for molting in O. volvulus L3 larvae.

  8. The Impacts of Climate Change Negotiation on Domestic Industrial Structure and International Competitiveness

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jae Kyu; Kang, Yoon Young [Korea Energy Economics Institute, Euiwang (Korea)

    2000-12-01

    The world community adopted the Kyoto Protocol in 1997 at the third Conference of the Parties to the United Nations Framework Convention on Climate Change(UNFCCC). The main achievement was agreement by developed(Annex I) countries to reduce or limit their greenhouse gas emissions. To assist parties in meeting their emission targets the Protocol sanctions the use of economic instruments such as the clean development mechanism(CDM), joint implementation(JI) and emissions trading(ET). However, there is still significant uncertainty surrounding the Kyoto Protocol for much of the details in the Protocol remains to be negotiated. The challenge now facing those negotiating the Kyoto Protocol is to remove the uncertainty and secure ratification of the Protocol. After the negotiation reaches an agreement in near future, the next main issue to be addressed is the way of involvement of developing countries in emission abatement commitments. The analysis presented in this report is based on the application of a global computable general equilibrium(CGE) model - GTEM-KOR. According to the analysis, compliance with Kyoto Protocol commitments, regardless of the emissions trading, is projected to impose economic costs on Annex I regions in the aggregate. Despite having no emission abatement commitments under the Kyoto Protocol, non-Annex I economies would be affected by emission abatement in Annex I regions undertaken as a result of entry into force of the Protocol. These effects would arise through trade and investment linkages between economies. Although the net impact for non-Annex I regions in aggregate is projected to be positive, there is a range of effects and the net impact for any one non-Annex I country will depend on its particular production and trade structure. As industrialized countries reduce their fossil fuel consumption to meet their emission reduction targets, their demand for fossil fuel imports from non-Annex I countries will decline, leading to lower fossil

  9. The impact of surface geometry, cavitation, and condensation on wetting transitions: posts and reentrant structures

    Science.gov (United States)

    Panter, J. R.; Kusumaatmaja, H.

    2017-03-01

    The fundamental impacts of surface geometry on the stability of wetting states, and the transitions between them are elucidated for square posts and reentrant structures in three dimensions. We identify three principal outcomes of particular importance for future surface design of liquid-repellent surfaces. Firstly, we demonstrate and quantify how capillary condensation and vapour cavitation affect wetting state stabilities. At high contact angles, cavitation is enhanced about wide, closely-spaced square posts, leading to the existence of suspended states without an associated collapsed state. At low contact angles, narrow reentrant pillars suppress condensation and enable the suspension of even highly wetting liquids. Secondly, two distinct collapse mechanisms are observed for 3D reentrant geometries, base contact and pillar contact, which are operative at different pillar heights. As well as morphological differences in the interface of the penetrating liquid, each mechanism is affected differently by changes in the contact angle with the solid. Finally, for highly-wetting liquids, condensates are shown to critically modify the transition pathways in both the base contact and pillar contact modes.

  10. Impact of quadrivalent human papillomavirus vaccine on genital warts in an opportunistic vaccination structure.

    Science.gov (United States)

    Lurie, Samuel; Mizrachi, Yossi; Chodick, Gabi; Katz, Rachel; Schejter, Eduardo

    2017-08-01

    Genital warts are the most common sexually transmitted disease and have a detrimental impact on quality of life. Genital warts could be prevented by prophylactic HPV vaccination. The objective was to study real-life benefit of opportunistic HPV vaccination on age and gender specific incidence of genital warts. We performed a register-based population cohort study from publicly funded health-care provider in Israel. The incidence of genital warts was assessed during three time frame intervals: 2006-2008 (pre-vaccination effect period) 2009-2012 (early post-vaccination effect period) and 2013-2015 (late post-vaccination effect period), with an average annual number of members of 1,765,481, 1,906,774 and 2,042,678 in the years 2006-2008, 2009-2012 and 2013-2015, respectively. Among females, annual incidence of genital warts per 100,000 women decreased from 210.43 to 161.71 (OR 0.76, 95%CI 0.71-0.82, pwarts per 100,000 men decreased from 262.85 to 232.40 (OR 0.88, 95%CI 0.83-0.93, pwarts even in opportunistic HPV vaccination structure. This information may be relevant for health-care providers in countries where national immunization programs do not include HPV vaccines. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Impact of long-term fertilization practice on soil structure evolution

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Møldrup, Per; Vogel, Hans-Jörg

    2014-01-01

    The study characterized soil structure development and evolution in six plots that were amended with varying amounts of animalmanure (AM) and NPK fertilizer over a period of 106 years in a long-termfertilization experiment in Bad Lauchstädt, Germany. Two intact soil cores (10-cm diameter and 8-cm...... tall) and bulk soil samples were extracted froma depth between 5 and 15-cmfromeach plot. Soil properties including texture, organic carbon, soil–water characteristic, air permeability and diffusivity were measured and analyzed along with X-ray computed tomography (CT) data. Long......-termapplications of AMand NPK had a major impact on soil organic carbon content which increased from 0.015 kg kg−1 (unfertilized plot) to 0.024 kg kg−1 (well fertilized plot, 30 T ha−1 2y−1 AM with NPK). Total porosity linearly followed the organic carbon gradient, increasing from 0.36 to 0.43 m3 m−3. The water holding...... capacity of the soil was considerably increased with the increase of AM and NPK applications. Gas diffusivity and air permeability measurements clearly indicated that the level of soil aeration improved with increasing AMand NPK fertilizer amount. The three-dimensional X-ray CT visualizations revealed...

  12. Structure-toxicity relationship of chloroacetanilide herbicides: relative impact on soil microorganisms.

    Science.gov (United States)

    Saha, Supradip; Dutta, Debashis; Karmakar, Rajib; Ray, Deb Prasad

    2012-09-01

    The research was carried out to ascertain the effect of three chloroacetanilide herbicides, alachlor, butachlor and pretilachlor on soil microbial biomass growth and activity. Laboratory experiments were performed in a silty clay loam soil to relate changes of soil enzymatic activity to the herbicide persistence under laboratory condition up to 42 days at three application rates. The results showed that all the three herbicides caused enhancement of dehydrogenase activity. Higher concentrations of herbicide resulted in enhancement of the enzymatic activity. In addition, a similar trend was observed in β-glucosidase and acid phosphatase activity, although urease activity decreased upon incubation for 42 days as compared with initial soil incubation values. Based on the extent of impact for dehydrogenase activity in soil, the order was pretilachlor>alachlor>butachlor; whereas in case of urease activity, the order changed to pretilachlor>butachlor>alachlor. The soil half-lives of alachlor, butachlor and pretilachlor respectively, were 9.3, 12.7 and 7.3 days, which could be accounted for in terms of their respective chemical structures, as well as variable adsorption, degradation, differential effects of the agents on soil microbes. Soil management practices and the differing physicochemical properties of the herbicides may contribute to their rates of decay in soil.

  13. Modeling the Impact of Drizzle and 3D Cloud Structure on Remote Sensing of Effective Radius

    Science.gov (United States)

    Platnick, Steven; Zinner, Tobias; Ackerman, S.

    2008-01-01

    Remote sensing of cloud particle size with passive sensors like MODIS is an important tool for cloud microphysical studies. As a measure of the radiatively relevant droplet size, effective radius can be retrieved with different combinations of visible through shortwave infrared channels. MODIS observations sometimes show significantly larger effective radii in marine boundary layer cloud fields derived from the 1.6 and 2.1 pm channel observations than for 3.7 pm retrievals. Possible explanations range from 3D radiative transport effects and sub-pixel cloud inhomogeneity to the impact of drizzle formation on the droplet distribution. To investigate the potential influence of these factors, we use LES boundary layer cloud simulations in combination with 3D Monte Carlo simulations of MODIS observations. LES simulations of warm cloud spectral microphysics for cases of marine stratus and broken stratocumulus, each for two different values of cloud condensation nuclei density, produce cloud structures comprising droplet size distributions with and without drizzle size drops. In this study, synthetic MODIS observations generated from 3D radiative transport simulations that consider the full droplet size distribution will be generated for each scene. The operational MODIS effective radius retrievals will then be applied to the simulated reflectances and the results compared with the LES microphysics.

  14. Contamination assessment in microbiological sampling of the Eyreville core, Chesapeake Bay impact structure

    Science.gov (United States)

    Gronstal, A.L.; Voytek, M.A.; Kirshtein, J.D.; Von der, Heyde; Lowit, M.D.; Cockell, C.S.

    2009-01-01

    Knowledge of the deep subsurface biosphere is limited due to difficulties in recovering materials. Deep drilling projects provide access to the subsurface; however, contamination introduced during drilling poses a major obstacle in obtaining clean samples. To monitor contamination during the 2005 International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) deep drilling of the Chesapeake Bay impact structure, four methods were utilized. Fluorescent microspheres were used to mimic the ability of contaminant cells to enter samples through fractures in the core material during retrieval. Drilling mud was infused with a chemical tracer (Halon 1211) in order to monitor penetration of mud into cores. Pore water from samples was examined using excitation-emission matrix (EEM) fl uorescence spectroscopy to characterize dissolved organic carbon (DOC) present at various depths. DOC signatures at depth were compared to signatures from drilling mud in order to identify potential contamination. Finally, microbial contaminants present in drilling mud were identified through 16S ribosomal deoxyribonucleic acid (rDNA) clone libraries and compared to species cultured from core samples. Together, these methods allowed us to categorize the recovered core samples according to the likelihood of contamination. Twenty-two of the 47 subcores that were retrieved were free of contamination by all the methods used and were subsequently used for microbiological culture and culture-independent analysis. Our approach provides a comprehensive assessment of both particulate and dissolved contaminants that could be applied to any environment with low biomass. ?? 2009 The Geological Society of America.

  15. Temporal Structures of the North Atlantic Oscillation and Its Impact on the Regional Climate Variability

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this study, the temporal structure of the variation of North Atlantic Oscillation (NAO) and its impact on regional climate variability are analyzed using various datasets. The results show that blocking formations in the Atlantic region are sensitive to the phase of the NAO. Sixty-seven percent more winter blocking days are observed during the negative phase compared to the positive phase of the NAO. The average length of blocking during the negative phase is about 11 days, which is nearly twice as long as the 6-day length observed during the positive phase of the NAO. The NAO-related differences in blocking frequency and persistence are associated with changes in the distribution of the surface air temperature anomaly, which, to a large extent, is determined by the phase of the NAO. The distribution of regional cloud amount is also sensitive to the phase of the NAO. For the negative phase, the cloud amounts are significant, positive anomalies in the convective zone in the Tropics and much less cloudiness in the mid latitudes. But for the positive phase of the NAO, the cloud amount is much higher in the mid-latitude storm track region. In the whole Atlantic region, the cloud amount shows a decrease with the increase of surface air temperature. These results suggest that there may be a negative feedback between the cloud amount and the surface air temperature in the Atlantic region.

  16. Impact of Scale Dependent Bias and Nonlinear Structure Growth on the ISW Effect: Angular Power Spectra

    CERN Document Server

    Smith, Robert E; Seljak, Uros

    2009-01-01

    We investigate the impact of nonlinear evolution of the gravitational potentials in the LCDM model on the Integrated Sachs-Wolfe (ISW) contribution to the CMB temperature power spectrum, and on the cross-power spectrum of the CMB and a set of biased tracers of the mass. We use an ensemble of N-body simulations to directly follow the potentials and compare results to perturbation theory (PT). The predictions from PT match the results to high precision for k100 the departures are more significant, however the CMB signal is more than a factor 10^3 larger at this scale. Nonlinear ISW effects therefore play no role in shaping the CMB power spectrum for l<1500. We analyze the CMB--density tracer cross-spectrum using simulations and renormalized bias PT, and find good agreement. The usual assumption is that nonlinear evolution enhances the growth of structure and counteracts linear ISW on small scales, leading to a change in sign of the CMB-LSS cross-spectrum at small scales. However, PT analysis suggests that th...

  17. Impact of the Extreme Warming of 2012 on Shelfbreak Frontal Structure North of Cape Hatteras

    Science.gov (United States)

    Gawarkiewickz, G.

    2014-12-01

    Continental shelf circulation north of Cape Hatteras is complex, with southward flowing Middle Atlantic Bight shelf water intersecting the Gulf Stream and subducting offshore into the Gulf Stream. In May, 2012, a cruise was conducted in order to study the shelf circulation and acoustic propagation through fish schools in the area. An important aspect of the study was to use Autonomous Underwater Vehicles to map fish schools with a sidescan sonar. High-resolution hydrographic surveys to map the continental shelf water masses and shelfbreak frontal structure were sampled to relate oceanographic conditions to the fish school distributions. The cold pool water mass over the continental shelf in May 2012 was extremely warm, with temperature anomalies of up to 5 Degrees C relative to observations from the same area in May, 1996. The normal cross-shelf temperature gradients within the shelfbreak front were not present because of the warming. As a result, the shelf density field was much more buoyant than usual, which led to an accelerated shelfbreak jet. Moored velocity measurements at the 60 m isobath recorded alongshelf flow of as much as 0.6 m/s. The anticipated fish species were not observed over the continental shelf. Some comments on the forcing leading to the large scale warming will be presented, along with a brief discussion of the impact of the warming on the marine ecosystem in the northeast U.S.

  18. Shock veins in the central uplift of the Manicouagan impact structure: Context and genesis

    Science.gov (United States)

    Biren, Marc B.; Spray, John G.

    2011-03-01

    We describe the development of shock veins that penetrate the anorthositic central uplift of the Manicouagan impact structure. They occur as thin (shatter cones, planar fractures and planar deformation features in various minerals. The shock veins at Manicouagan share many similarities with vein systems developed in meteorites. They also provide an in situ context with which to better understand meteoroid source and lofting conditions. In addition to containing high pressure phases, the shock veins exhibit evidence for high temperature partial melting of host silicate clasts, with the generation of flow-textured fragments and glasses. The formation of microcrystallites and dendrites from some melts indicates rapid cooling. We propose a two-stage generation mechanism comprising an initial high-pressure shock excursion (estimated to last < 0.5 s based on projectile size considerations) followed by a longer high-temperature pulse of a few seconds duration. We suggest that the shock excursion is initiated by target heterogeneities that cause distortions in the hemispherically propagating shock front. This results in radially oriented tearing and vein formation with shock amplification occurring via intra-vein shock reverberation. High-speed displacement along the veins is driven by stress release on rarefaction, which results in frictional melting via adiabatic heating.

  19. Impact of a rural solar electrification project on the level and structure of women’s empowerment

    Science.gov (United States)

    Burney, Jennifer; Alaofè, Halimatou; Naylor, Rosamond; Taren, Douglas

    2017-09-01

    Although development organizations agree that reliable access to energy and energy services—one of the 17 Sustainable Development Goals—is likely to have profound and perhaps disproportionate impacts on women, few studies have directly empirically estimated the impact of energy access on women’s empowerment. This is a result of both a relative dearth of energy access evaluations in general and a lack of clarity on how to quantify gender impacts of development projects. Here we present an evaluation of the impacts of the Solar Market Garden—a distributed photovoltaic irrigation project—on the level and structure of women’s empowerment in Benin, West Africa. We use a quasi-experimental design (matched-pair villages) to estimate changes in empowerment for project beneficiaries after one year of Solar Market Garden production relative to non-beneficiaries in both treatment and comparison villages (n = 771). To create an empowerment metric, we constructed a set of general questions based on existing theories of empowerment, and then used latent variable analysis to understand the underlying structure of empowerment locally. We repeated this analysis at follow-up to understand whether the structure of empowerment had changed over time, and then measured changes in both the levels and likelihood of empowerment over time. We show that the Solar Market Garden significantly positively impacted women’s empowerment, particularly through the domain of economic independence. In addition to providing rigorous evidence for the impact of a rural renewable energy project on women’s empowerment, our work lays out a methodology that can be used in the future to benchmark the gender impacts of energy projects.

  20. Lab-scale impact test to investigate the pipe-soil interaction and comparative study to evaluate structural responses

    Directory of Open Access Journals (Sweden)

    Ryu Dong-Man

    2015-07-01

    Full Text Available This study examined the dynamic response of a subsea pipeline under an impact load to determine the effect of the seabed soil. A laboratory-scale soil-based pipeline impact test was carried out to investigate the pipeline deformation/strain as well as the interaction with the soil-pipeline. In addition, an impact test was simulated using the finite element technique, and the calculated strain was compared with the experimental results. During the simulation, the pipeline was described based on an elasto-plastic analysis, and the soil was modeled using the Mohr-Coulomb failure criterion. The results obtained were compared with ASME D31.8, and the differences between the analysis results and the rules were specifically investigated. Modified ASME formulae were proposed to calculate the precise structural behavior of a subsea pipeline under an impact load when considering sand- and clay-based seabed soils.

  1. Lab-scale impact test to investigate the pipe-soil interaction and comparative study to evaluate structural responses

    Directory of Open Access Journals (Sweden)

    Dong-Man Ryu

    2015-07-01

    Full Text Available This study examined the dynamic response of a subsea pipeline under an impact load to determine the effect of the seabed soil. A laboratory-scale soil-based pipeline impact test was carried out to investigate the pipeline deformation/strain as well as the interaction with the soil-pipeline. In addition, an impact test was simulated using the finite element technique, and the calculated strain was compared with the experimental results. During the simulation, the pipeline was described based on an elasto-plastic analysis, and the soil was modeled using the Mohr-Coulomb fail-ure criterion. The results obtained were compared with ASME D31.8, and the differences between the analysis results and the rules were specifically investigated. Modified ASME formulae were proposed to calculate the precise structural behavior of a subsea pipeline under an impact load when considering sand- and clay-based seabed soils.

  2. Steel Processing Properties and Their Effect on Impact Deformation of Lightweight Structures

    Energy Technology Data Exchange (ETDEWEB)

    Simunovic, S

    2003-09-23

    The objective of the research was to perform a comprehensive computational analysis of the effects of material and process modeling approaches on performance of UltraLight Steel Auto Body (ULSAB) vehicle models. The research addressed numerous material related effects, impact conditions as well as analyzed the performance of the ULSAB vehicles in crashes against designs representing the current US vehicle fleet. This report is organized into three main sections. The first section describes the results of the computational analysis of ULSAB crash simulations that were performed using advanced material modeling techniques. The effects of strain-rate sensitivity on a high strength steel (HSS) intensive vehicle were analyzed. Frontal and frontal offset crash scenarios were used in a finite element parametric study of the ULSAB body structure. Comparisons are made between the crash results using the piece-wise-linear isotropic plasticity strain-rate dependent material model, and the isotropic plasticity material model based on quasi-static properties. The simulation results show the importance of advanced material modeling techniques for vehicle crash simulations due to strain-rate sensitivity and rapid hardening characteristics of advanced high strength steels. Material substitution was investigated for the main frontal crush structure using the material of similar yield stress a significantly different strain-rate and hardening characteristics. The objective of the research presented in Section 2 was to assess the influence of stamping process on crash response of ULSAB vehicle. Considered forming effects included thickness variations and plastic strain hardening imparted in the part forming process. The as-formed thickness and plastic strain for front crash parts were used as input data for vehicle crash analysis. Differences in structural performance between crash models with and without forming data were analyzed in order to determine the effects and feasibility of

  3. A Preliminary Geochemical Study of Crystalline Melt from the Manson Impact Structure

    Science.gov (United States)

    Korotev, R. L.; Jolliff, B. L.; Rockow, K. M.; Haskin, L. A.; Crossey, L. J.

    1993-07-01

    Although the Manson impact structure (35 km in diameter) in Iowa is of general interest because its age coincides with the end of the Cretaceous Period [1,2], it also provides an opportunity to study systematically the effects of a single, moderate-sized impact in a setting where the preimpact geology is reasonably well understood. We are interested in the extent of compositional uniformity in melt produced in large impacts and the causes of any compositional variation among different small samples of crystalline melt breccia. This understanding is useful for interpretation of data from lunar impact-melt breccias, for which we have less geologic control. We have obtained concentrations of ~30 elements in samples from the M-1 core taken on the flank of the central peak of the Manson impact structure in Iowa [3-6]. The sample set consists of 49 representative samples of breccia matrix determined (by visual inspection) to contain minimal mineralized vugs, fractures, or large or altered clasts [5]. The core consists of three principal units [3]: sedimentary clast breccia (SCB), 54-106-m depth; crystalline clast breccia, melt matrix (CCB-M), 106- 147-m depth; and crystalline clast breccia, sandy matrix (CCB-S), 163-214-m depth; there is an ~16-m "transition zone" between CCB-M and CCB-S. The sandy- matrix breccias, which are believed to be "in-situ brecciated basement with injected melt and shale fragments" [4], may be the equivalent of lunar "fragmental breccias" [e.g., 7]. They contain large clasts, some bigger than the core diameter, and, consequently, are variable in composition at the sample mass studied here (1-4 g). Samples of the overlying melt-matrix breccias (CCB-M) are more uniform in composition. However, the concentrations of some elements (Na, Ca, Sc, Cr, Fe, and Co) generally increase with depth through CCB-M (unit 1 of [4]), while other elements decrease (K, Sb, Cs, La, Hf, and Ta). These trends continue through the transition zone to the CCB-S. Thus

  4. A comparative analysis of two Early Palaeozoic marine impact structures in Estonia, Baltic Sea: Neugrund and Kärdla

    Directory of Open Access Journals (Sweden)

    Sten Suuroja

    2013-07-01

    Full Text Available Kärdla and Neugrund are two Early Palaeozoic offshore impact structures located some 50 km apart along the Estonian coast of the Baltic Sea. They share many similarities but differing features are also found. The Kärdla impact structure is located at the NE coastof Hiiumaa Island (58°58’N, 22°46’E. The inner crater has a 4 km rim-to-rim diameter and a c. 130 m high central uplift, surrounded by a ring fault, c. 12 km in diameter. The well-preserved buried inner crater is outlined in the landscape by a circular ridge of upliftedbedrock. The perimeter of the outer crater is outlined on the seafloor by a semicircular ridge of narrow shoals. The variable height of the rim wall (50–240 m above the crystalline basement level and the asymmetric location of the inner crater is obviously a result of an oblique impact in a layered target and partial collapse of the rim wall. Shortly after the impact in a shallow epicontinental sea during Late Ordovician time (c. 455 My, calcareous biodetritic muds were deposited and the crater was buried. The Neugrund impact structure is located in the seabed at the entrance of the Gulf of Finland (59°20’N, 23°31’E. The inner crater has a 7 km rim-to-rim diameter and the outer limit of the structure passes through the Osmussaar Island to the southwest of the impact centre. The crater wasburied in a shallow epicontinental sea with siliciclastic deposition shortly after the impact at Early Cambrian time, c. 535 My. It was partially re-exposed by erosion during Pliocene. The target had a three-layered composition: Precambrian metamorphic rocks covered byEdiacaran and Early Cambrian siliciclastic rocks (c. 150 m and water (c. 100 m. The structure has been studied with seismoacoustic and sidescan sonar profiling, and by diving and sampling of submarine outcrops. Several hundred samples of impact breccias have been collected and investigated from erratic boulders distributed by glacial action in the west

  5. Impact of land-use change and hard structures on the evolution of fringing marsh shorelines

    Science.gov (United States)

    Mattheus, Christopher R.; Rodriguez, Antonio B.; McKee, Brent A.; Currin, Carolyn A.

    2010-07-01

    Estuarine fringe marshes provide essential ecosystem services to coastal regions, including carbon sequestration and provision of shelter and nursery grounds for aquatic and terrestrial animals. The ability of a marsh to sustain itself by vertical accretion in response to sea-level rise is, in part, limited by inorganic sediment supply. Models attempting to forecast salt-marsh response to future sea-level rise commonly ignore land-use changes, despite the recent coastal population boom and the potential of land-use changes to alter sediment sources and modify established sediment-transport pathways. This study investigates the impacts of landscape modifications, which are typical of coastal areas, on the nearshore sedimentation and edge evolution of two fringing marshes. The sites examined include a marsh fringing the upper bay and a marsh fringing a beach ridge on the estuarine shoreline of a barrier island. Both sites are located in the same estuarine system, have similar hydrologic settings and comparable vegetation densities. Previous work, marsh cores, and a historical record from aerial photos indicate that although the fringe marshes are in different geomorphic locations, prior to anthropogenic modifications they were similar in terms of nearshore-sediment composition, scarp-shoreline morphology, and shoreline trajectory. The upper-bay marsh was impacted by the introduction of tree farming in the watershed of a tributary creek to the upper bay, which increased upland erosion and caused higher sedimentation rates in the estuary. The back-barrier marsh, which received no contribution from the tree farm because it is distal with respect to river input, was modified by the installation of a pier and rock sill. Terrestrial LIDAR, surface elevation tables, and accretion rates obtained from radioisotope analyses show that the deforestation induced high rates of nearshore and marsh accretion at the upper-bay site, which is promoting marsh colonization and expansion

  6. Citation impacts revisited: how novel impact measures reflect interdisciplinarity and structural change at the local and global level

    CERN Document Server

    Zitt, Michel

    2013-01-01

    Citation networks have fed numerous works in scientific evaluation, science mapping (and more recently large-scale network studies) for decades. The variety of citation behavior across scientific fields is both a research topic in sociology of science, and a problem in scientific evaluation. Normalization, tantamount to a particular weighting of links in the citation network, is necessary for allowing across-field comparisons of citation scores and interdisciplinary studies. In addition to classical normalization which drastically reduces all variability factors altogether, two tracks of research have emerged in the recent years. One is the revival of iterative "influence measures". The second is the "citing-side" normalization, whose only purpose is to control for the main factor of variability, the inequality in citing propensity, letting other aspects play: knowledge export/imports and growth. When all variables are defined at the same field-level, two propositions are established: (a) the gross impact mea...

  7. Vargeão Dome Impact Crater and the Cerro do Jarau Structure (Brazil) — A First Report After Recent Fieldwork

    Science.gov (United States)

    Zaag, P. T.; Reimold, W. U.; de Oliveira, G. J. G.; Crósta, A. P.

    2016-08-01

    Impact craters in volcanic targets are significantly underrepresented on Earth but are prominent features on other planets. We investigated two structures (Brazil) in volcanics, in particular targeting structural geological observations.

  8. The Impact of Retail Rate Structures on the Economics ofCommercial Photovoltaic Systems in California

    Energy Technology Data Exchange (ETDEWEB)

    Wiser, Ryan; Mills, Andrew; Barbose, Galen; Golove, William

    2007-07-03

    To achieve a sizable and self-sustaining market for grid-connected, customer-sited photovoltaic (PV) systems, solar will likely need to be competitive with retail electricity rates. In this report, we examine the impact of retail rate design on the economic value of commercial PV systems in California. Using 15-minute interval building load and PV production data from 24 actual commercial PV installations, we compare the value of the bill savings across 20 commercial customer retail rates currently offered in the state. We find that the specifics of the rate structure, combined with the characteristics of the customer's underlying load and the size of the PV system, can have a substantial impact on the customer-economics of commercial PV systems. Key conclusions for policymakers that emerge from our analysis are as follows: {sm_bullet} Rate design is fundamental to the economics of commercial PV. The rate-reduction value of PV for our sample of commercial customers, considering all available retail tariffs, ranges from $0.05/kWh to $0.24/kWh, reflecting differences in rate structures, the revenue requirements of the various utilities, the size of the PV system relative to building load, and customer load shapes. For the average customer in our sample, differences in rate structure, alone, alter the value of PV by 25% to 75%, depending on the size of the PV system relative to building load. {sm_bullet} TOU-based energy-focused rates can provide substantial value to many PV customers. Retail rates that wrap all or most utility cost recovery needs into time-of-use (TOU)-based volumetric energy rates, and which exclude or limit demand-based charges, provide the most value to PV systems across a wide variety of circumstances. Expanding the availability of such rates will increase the value of many commercial PV systems. {sm_bullet} Offering commercial customers a variety of rate options would be of value to PV. Despite the advantages of energy-focused rates for PV

  9. A rapid method for identifying and characterizing structural impacts using distributed sensors: An application for automotive pedestrian protection

    Science.gov (United States)

    Kim, Andrew C.

    This research is motivated by recent activity to improve automotive safety, especially for pedestrians. In many parts of the world today, injuries and fatalities from road accidents are a significant problem. Safety features such as seat restraints and air bags provide considerable levels of protection for car occupants; however, no such protective measures currently exist for pedestrians. Drawing upon the success and effectiveness of occupant air bag systems, current research aims to develop similar devices for pedestrians. These active pedestrian protection systems deploy a safety feature such as an external air bag when a pedestrian is hit by a vehicle. Contact with the front bumper induces a body rotation that may result in a violent head collision. The deployable safety device provides a cushioning surface for the vulnerable pedestrian during impact. The challenge of such a system is an effective sensory unit that can rapidly and correctly discriminate pedestrian impacts from non-pedestrian ones. The fast kinematics of the automobile-pedestrian impact leaves a minimal amount of time for signal processing and computation. This research study focuses on a discrimination scheme that satisfies both the time and accuracy requirements for a proposed sensory system for pedestrian protection. A unique methodology was developed to identify structural impacts using dominant frequency features extracted from sensory data. Contact sensors mounted on the front bumper of an automobile measure the strain response from an impact event. The dominant frequencies obtained from these sensor signals are greatly influenced by the impact object's properties and can be used to discriminate between different objects. Extensive tests were conducted to gather sensor data and validate the proposed methodology and impact discrimination algorithm. Results of the impact tests indicate that the approach is sound, and the sensory system effectively identifies "pedestrian" impacts within a

  10. Predicting the Impact of Rock Blasting on Building Structures at Awunakrom in the Ahanta West District of Ghana

    Directory of Open Access Journals (Sweden)

    K.J. Bansah

    2014-07-01

    Full Text Available Blasting is an important process after drilling is completed in hard rock mining. It involves placing explosives in drill holes and detonating them to cause explosion. The energy released during this process fragments the rocks into sizes for desired end use. The detonation of these explosives may produce undesirable effects such as ground vibration which is capable of causing damage to building structures. It is therefore, necessary to conduct blast impact studies to determine potential impact of blast induced ground vibration prior to mining and establish remediation techniques. Blast impact study was conducted at Awunakrom in the Ahanta West District of Ghana. Building structures within the study area were mapped and characterized. A blast impact prediction model was also generated. Blast induced vibrations that may propagate from the Father Brown pit of Golden Star Wassa Limited using various instantaneous charges were determined. It was found that bench blasting at the Father Brown pit has a potential of causing damage to building structures within the Awunakrom community if the maximum instantaneous charge adopted at the southernmost periphery of the pit exceeds 30 kg. It was therefore, recommended that all bench blast conducted at the southern periphery of the Father Brown pit should adopt a maximum instantaneous charge of 30 kg to avert any potential blast damage. However, variable instantaneous charges of more than 30 kg can be adopted as the blast location moves towards the northern periphery.

  11. Hydrological drought across the world: impact of climate and physical catchment structure

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    H. A. J. Van Lanen

    2013-05-01

    Full Text Available Large-scale hydrological drought studies have demonstrated spatial and temporal patterns in observed trends, and considerable difference exists among global hydrological models in their ability to reproduce these patterns. In this study a controlled modeling experiment has been set up to systematically explore the role of climate and physical catchment structure (soils and groundwater systems to better understand underlying drought-generating mechanisms. Daily climate data (1958–2001 of 1495 grid cells across the world were selected that represent Köppen–Geiger major climate types. These data were fed into a conceptual hydrological model. Nine realizations of physical catchment structure were defined for each grid cell, i.e., three soils with different soil moisture supply capacity and three groundwater systems (quickly, intermediately and slowly responding. Hydrological drought characteristics (number, duration and standardized deficit volume were identified from time series of daily discharge. Summary statistics showed that the equatorial and temperate climate types (A- and C-climates had about twice as many drought events as the arid and polar types (B- and E-climates, and the durations of more extreme droughts were about half the length. Selected soils under permanent grassland were found to have a minor effect on hydrological drought characteristics, whereas groundwater systems had major impact. Groundwater systems strongly controlled the hydrological drought characteristics of all climate types, but particularly those of the wetter A-, C- and D-climates because of higher recharge. The median number of droughts for quickly responding groundwater systems was about three times higher than for slowly responding systems. Groundwater systems substantially affected the duration, particularly of the more extreme drought events. Bivariate probability distributions of drought duration and standardized deficit for combinations of K

  12. Hydrological drought across the world: impact of climate and physical catchment structure

    Directory of Open Access Journals (Sweden)

    H. A. J. Van Lanen

    2012-10-01

    Full Text Available Large-scale hydrological drought studies have demonstrated spatial and temporal patterns in observed trends and considerable difference exists among global hydrological models in their ability to reproduce these patterns. A controlled modeling experiment has been set up to systematically explore the role of climate and physical catchment structure (soils and groundwater systems to better understand underlying drought-generating mechanisms. Daily climate data (1958–2001 of 1495 grid cells across the world were selected that represent Köppen-Geiger major climate types. These data were fed into a hydrological model. Nine realizations of physical catchment structure were defined for each grid cell, i.e. three soils with different soil moisture supply capacity and three groundwater systems (quickly-, intermediary- and slowly-responding. Hydrological drought characteristics (number, duration and standardized deficit volume were identified from time series of daily discharge. Summary statistics showed that the equatorial and temperate climate types (A- and C-climates had about twice as many drought events as the arid and polar types (B- and E-climates and the duration of more extreme droughts were about half the length. Soils were found to have a minor effect on hydrological drought characteristics, whereas groundwater systems had major impact. Groundwater systems strongly controlled the hydrological drought characteristics of all climate types, but particularly those of the wetter A-, C- and D-climates because of higher recharge. The median number of drought for quickly-responding groundwater systems was about three times higher than for slowly-responding systems, which substantially affected the duration, particularly of the more extreme drought events. Bivariate probability distributions of drought duration and standardized deficit for combinations of Köppen-Geiger climate, soil and groundwater system showed that responsiveness of groundwater

  13. Sea ice edge position impact on the atmospheric boundary layer temperature structure

    Science.gov (United States)

    Khavina, Elena; Repina, Irina

    2016-04-01

    temperature on heights from 0 to 1000 m. (time resolution 5 min., height resolution 50 m.). Results: 1) The structure of atmospheric temperature changes rapidly while the vessel is crossing the sea ice edge; 2) The impact of the underlying surface on the atmosphere above it was registered on the heights from 0 to 1000 meters; 3) The data on ice edge position obtained from the satellite and from the vessel varies greatly. Those discrepancies affect the further processing and analysis of data significantly and might cause the errors in models' development.

  14. Impact of male infanticide on the social structure of mountain gorillas.

    Science.gov (United States)

    Robbins, Andrew M; Gray, Maryke; Basabose, Augustin; Uwingeli, Prosper; Mburanumwe, Innocent; Kagoda, Edwin; Robbins, Martha M

    2013-01-01

    Infanticide can be a major influence upon the social structure of species in which females maintain long-term associations with males. Previous studies have suggested that female mountain gorillas benefit from residing in multimale groups because infanticide occurs when one-male groups disintegrate after the dominant male dies. Here we measure the impact of infanticide on the reproductive success of female mountain gorillas, and we examine whether their dispersal patterns reflect a strategy to avoid infanticide. Using more than 40 years of data from up to 70% of the entire population, we found that only 1.7% of the infants that were born in the study had died from infanticide during group disintegrations. The rarity of such infanticide mainly reflects a low mortality rate of dominant males in one-male groups, and it does not dispel previous observations that infanticide occurs during group disintegrations. After including infanticide from causes other than group disintegrations, infanticide victims represented up to 5.5% of the offspring born during the study, and they accounted for up to 21% of infant mortality. The overall rates of infanticide were 2-3 times higher in one-male groups than multimale groups, but those differences were not statistically significant. Infant mortality, the length of interbirth intervals, and the age of first reproduction were not significantly different between one-male versus multimale groups, so we found no significant fitness benefits for females to prefer multimale groups. In addition, we found limited evidence that female dispersal patterns reflect a preference for multimale groups. If the strength of selection is modest for females to avoid group disintegrations, than any preference for multimale groups may be slow to evolve. Alternatively, variability in male strength might give some one-male groups a lower infanticide risk than some multimale groups, which could explain why both types of groups remain common.

  15. Impact of male infanticide on the social structure of mountain gorillas.

    Directory of Open Access Journals (Sweden)

    Andrew M Robbins

    Full Text Available Infanticide can be a major influence upon the social structure of species in which females maintain long-term associations with males. Previous studies have suggested that female mountain gorillas benefit from residing in multimale groups because infanticide occurs when one-male groups disintegrate after the dominant male dies. Here we measure the impact of infanticide on the reproductive success of female mountain gorillas, and we examine whether their dispersal patterns reflect a strategy to avoid infanticide. Using more than 40 years of data from up to 70% of the entire population, we found that only 1.7% of the infants that were born in the study had died from infanticide during group disintegrations. The rarity of such infanticide mainly reflects a low mortality rate of dominant males in one-male groups, and it does not dispel previous observations that infanticide occurs during group disintegrations. After including infanticide from causes other than group disintegrations, infanticide victims represented up to 5.5% of the offspring born during the study, and they accounted for up to 21% of infant mortality. The overall rates of infanticide were 2-3 times higher in one-male groups than multimale groups, but those differences were not statistically significant. Infant mortality, the length of interbirth intervals, and the age of first reproduction were not significantly different between one-male versus multimale groups, so we found no significant fitness benefits for females to prefer multimale groups. In addition, we found limited evidence that female dispersal patterns reflect a preference for multimale groups. If the strength of selection is modest for females to avoid group disintegrations, than any preference for multimale groups may be slow to evolve. Alternatively, variability in male strength might give some one-male groups a lower infanticide risk than some multimale groups, which could explain why both types of groups remain

  16. Impact of high pCO2 on shell structure of the bivalve Cerastoderma edule.

    Science.gov (United States)

    Milano, Stefania; Schöne, Bernd R; Wang, Schunfeng; Müller, Werner E

    2016-08-01

    Raised atmospheric emissions of carbon dioxide (CO2) result in an increased ocean pCO2 level and decreased carbonate saturation state. Ocean acidification potentially represents a major threat to calcifying organisms, specifically mollusks. The present study focuses on the impact of elevated pCO2 on shell microstructural and mechanical properties of the bivalve Cerastoderma edule. The mollusks were collected from the Baltic Sea and kept in flow-through systems at six different pCO2 levels from 900 μatm (control) to 24,400 μatm. Extreme pCO2 levels were used to determine the effects of potential leaks from the carbon capture and sequestration sites where CO2 is stored in sub-seabed geological formations. Two approaches were combined to determine the effects of the acidified conditions: (1) Shell microstructures and dissolution damage were analyzed using scanning electron microscopy (SEM) and (2) shell hardness was tested using nanoindentation. Microstructures of specimens reared at different pCO2 levels do not show significant changes in their size and shape. Likewise, the increase of pCO2 does not affect shell hardness. However, dissolution of ontogenetically younger portions of the shell becomes more severe with the increase of pCO2. Irrespective of pCO2, strong negative correlations exist between microstructure size and shell mechanics. An additional sample from the North Sea revealed the same microstructural-mechanical interdependency as the shells from the Baltic Sea. Our findings suggest that the skeletal structure of C. edule is not intensely influenced by pCO2 variations. Furthermore, our study indicates that naturally occurring shell mechanical property depends on the shell architecture at μm-scale.

  17. The Impact of Microphysics on Intensity and Structure of Hurricanes and Mesoscale Convective Systems

    Science.gov (United States)

    Tao, Wei-Kuo; Shi, Jainn J.; Jou, Ben Jong-Dao; Lee, Wen-Chau; Lin, Pay-Liam; Chang, Mei-Yu

    2007-01-01

    During the past decade, both research and operational numerical weather prediction models, e.g. Weather Research and Forecast (WRF) model, have started using more complex microphysical schemes originally developed for high-resolution cloud resolving models (CRMs) with a 1-2 km or less horizontal resolutions. WRF is a next-generation mesoscale forecast model and assimilation system that has incorporated modern software framework, advanced dynamics, numeric and data assimilation techniques, a multiple moveable nesting capability, and improved physical packages. WRF model can be used for a wide range of applications, from idealized research to operational forecasting, with an emphasis on horizontal grid sizes in the range of 1-10 km. The current WRF includes several different microphysics options such as Purdue Lin et al. (1983), WSM 6-class and Thompson microphysics schemes. We have recently implemented three sophisticated cloud microphysics schemes into WRF. The cloud microphysics schemes have been extensively tested and applied for different mesoscale systems in different geographical locations. The performances of these schemes have been compared to those from other WRF microphysics options. We are performing sensitivity tests in using WRF to examine the impact of six different cloud microphysical schemes on precipitation processes associated hurricanes and mesoscale convective systems developed at different geographic locations [Oklahoma (IHOP), Louisiana (Hurricane Katrina), Canada (C3VP - snow events), Washington (fire storm), India (Monsoon), Taiwan (TiMREX - terrain)]. We will determine the microphysical schemes for good simulated convective systems in these geographic locations. We are also performing the inline tracer calculation to comprehend the physical processes (i.e., boundary layer and each quadrant in the boundary layer) related to the development and structure of hurricanes and mesoscale convective systems.

  18. Impact of rural residence and health system structure on quality of liver care.

    Directory of Open Access Journals (Sweden)

    Catherine Rongey

    Full Text Available BACKGROUND: Specialist physician concentration in urban areas can affect access and quality of care for rural patients. As effective drug treatment for hepatitis C (HCV becomes increasingly available, the extent to which rural patients needing HCV specialists face access or quality deficits is unknown. We sought to determine the influence of rural residency on access to HCV specialists and quality of liver care. METHODS: The study used a national cohort of 151,965 Veterans Health Administration (VHA patients with HCV starting in 2005 and followed to 2009. The VHA's constant national benefit structure reduces the impact of insurance as an explanation for observed disparities. Multivariate cox proportion regression models for each quality indicator were performed. RESULTS: Thirty percent of VHA patients with HCV reside in rural and highly rural areas. Compared to urban residents, highly rural (HR 0.70, CI 0.65-0.75 and rural (HR 0.96, CI 0.94-0.97 residents were significantly less likely to access HCV specialty care. The quality indicators were more mixed. While rural residents were less likely to receive HIV screening, there were no significant differences in hepatitis vaccinations, endoscopic variceal and hepatocellular carcinoma screening between the geographic subgroups. Of note, highly rural (HR 1.31, CI 1.14-1.50 and rural residents (HR 1.06, CI 1.02-1.10 were more likely to receive HCV therapy. Of those treated for HCV, a third received therapy from a non-specialist provider. CONCLUSION: Rural patients have less access to HCV specialists, but this does not necessarily translate to quality deficits. The VHA's efforts to improve specialty care access, rural patient behavior and decentralization of HCV therapy beyond specialty providers may explain this contradiction. Lessons learned within the VHA are critical for US healthcare systems restructuring into accountable care organizations that acquire features of integrated systems.

  19. Impact of exporting dependence on livestock production systems, industry structure, and research.

    Science.gov (United States)

    Macmillan, K L; Kirton, A H

    1997-02-01

    From 84 to 93% of New Zealand's annual production from livestock is exported to over 100 markets throughout the world. This export dependence has produced production systems that are low-cost because the Mediterranean maritime climate allows animals to graze outdoors throughout the year without provision for housing and with minimal requirements for cropping, harvesting, and forage storage. These systems exploit the inherent tendencies for ruminants to have annual production cycles that can be synchronized to use the seasonal availability of pasture, but this means that processing facilities must handle peak supply for brief periods. Processing technology can reduce the impact of peaks in supply that may not match market demand. The disadvantages of seasonality in processing costs are outweighed by lower production costs, as well as by the opportunity to manage large numbers of animals per labor unit. Cooperative structures that are owned by livestock producers are a common feature, especially in New Zealand's dairy industry. This continued preference for cooperatives may reflect the need to have a guaranteed processor for a perishable product such as milk, as well as sharing the risk in an export industry that has scant control over prices received. In addition, management systems for ruminant livestock can only respond slowly to changes in market demand because their production cycles last at least 12 mo and only one or two offspring are produced in each cycle. Export marketing of livestock products is complicated by trade bar